diff --git a/mineru/model/flash/html/document.py b/mineru/model/flash/html/document.py
index 117395e4..3bb94468 100644
--- a/mineru/model/flash/html/document.py
+++ b/mineru/model/flash/html/document.py
@@ -105,8 +105,12 @@ def parse_html_document(file_bytes: bytes, source_context: HtmlSourceContext | N
             continue
         name = local_name(element)
         if name == "style":
+            if _has_discarded_active_ancestor(element):
+                continue
             stylesheets.append(HtmlStylesheetSource("inline", "".join(element.itertext())))
         elif name == "link" and "stylesheet" in (element.get("rel") or "").casefold().split():
+            if _has_discarded_active_ancestor(element):
+                continue
             if href := (element.get("href") or "").strip():
                 stylesheets.append(HtmlStylesheetSource("link", href))
     base_href = next(
@@ -237,6 +241,11 @@ def _collapsed_text(element: etree._Element) -> str:
     return re.sub(r"\s+", " ", "".join(element.itertext())).strip()
 
 
+def _has_discarded_active_ancestor(element: etree._Element) -> bool:
+    """判断元素是否位于稍后会整棵删除的活动内容祖先中。"""
+    return any(isinstance(ancestor.tag, str) and local_name(ancestor) in _ACTIVE_TAGS for ancestor in element.iterancestors())
+
+
 def _normalize_formula_sources(root: etree._Element) -> None:
     """按共享优先级把成功来源收敛为携带裸 LaTeX 的静态 math 元素。"""
     _preserve_asciimath_text(root)
diff --git a/mineru/model/flash/html/selector.py b/mineru/model/flash/html/selector.py
index bc72b7cd..9a9c2d71 100644
--- a/mineru/model/flash/html/selector.py
+++ b/mineru/model/flash/html/selector.py
@@ -86,6 +86,17 @@ class _ScoredCandidate:
     explicit: bool
 
 
+@dataclass(frozen=True, slots=True)
+class _SoftPruneMetrics:
+    """保存 soft prune 所需的规范文本段、链接文本和语义对象统计。"""
+
+    text_chars: int = 0
+    text_segments: int = 0
+    link_chars: int = 0
+    link_count: int = 0
+    semantic_count: int = 0
+
+
 def select_auto_content(body: etree._Element, stylesheet: MarkupStylesheet) -> ContentSelection:
     """高置信选择正文候选，任一保守门槛失败时回退完整 body。"""
     metrics_by_element: dict[etree._Element, CandidateMetrics] = {}
@@ -321,28 +332,62 @@ def _is_containment_equivalent(first: _ScoredCandidate, second: _ScoredCandidate
 
 def _soft_prune(root: etree._Element) -> None:
     """在候选副本中删除确定的导航/表单和高噪声 token 子树。"""
+    metrics_by_element = _collect_soft_prune_metrics(root)
     for element in list(root.iterdescendants()):
         if not isinstance(element.tag, str):
             continue
         name = local_name(element)
         tokens = _tokens(element)
-        valuable = any(
-            isinstance(child.tag, str) and local_name(child) in _SEMANTIC_TAGS for child in element.iterdescendants()
-        )
-        text = _normalized_text(" ".join(element.itertext()))
-        links = " ".join(
-            " ".join(link.itertext())
-            for link in element.iterdescendants()
-            if isinstance(link.tag, str) and local_name(link) == "a"
-        )
-        link_density = len(_normalized_text(links)) / max(1, len(text))
+        metrics = metrics_by_element[element]
+        valuable = metrics.semantic_count > (1 if name in _SEMANTIC_TAGS else 0)
+        text_chars = metrics.text_chars + max(0, metrics.text_segments - 1)
+        link_chars = metrics.link_chars + max(0, metrics.link_count - 1)
+        link_density = link_chars / max(1, text_chars)
         should_remove = name in _BOILERPLATE_TAGS or (
-            bool(tokens & _NEGATIVE_TOKENS) and not valuable and (len(text) < 200 or link_density > 0.5)
+            bool(tokens & _NEGATIVE_TOKENS) and not valuable and (text_chars < 200 or link_density > 0.5)
         )
         if should_remove:
             _drop_tree_preserve_tail(element)
 
 
+def _collect_soft_prune_metrics(root: etree._Element) -> dict[etree._Element, _SoftPruneMetrics]:
+    """单次后序遍历预计算每个元素的完整子树文本、链接和语义对象统计。"""
+    elements = [element for element in root.iter() if isinstance(element.tag, str)]
+    output: dict[etree._Element, _SoftPruneMetrics] = {}
+    for element in reversed(elements):
+        own_text = _normalized_text(element.text)
+        text_chars = len(own_text)
+        text_segments = 1 if own_text else 0
+        link_chars = 0
+        link_count = 0
+        semantic_count = 1 if local_name(element) in _SEMANTIC_TAGS else 0
+        for child in element:
+            if isinstance(child.tag, str):
+                child_metrics = output[child]
+                text_chars += child_metrics.text_chars
+                text_segments += child_metrics.text_segments
+                link_chars += child_metrics.link_chars
+                link_count += child_metrics.link_count
+                semantic_count += child_metrics.semantic_count
+                if local_name(child) == "a":
+                    child_text_chars = child_metrics.text_chars + max(0, child_metrics.text_segments - 1)
+                    if child_text_chars:
+                        link_chars += child_text_chars
+                        link_count += 1
+            tail = _normalized_text(child.tail)
+            if tail:
+                text_chars += len(tail)
+                text_segments += 1
+        output[element] = _SoftPruneMetrics(
+            text_chars=text_chars,
+            text_segments=text_segments,
+            link_chars=link_chars,
+            link_count=link_count,
+            semantic_count=semantic_count,
+        )
+    return output
+
+
 def _drop_tree_preserve_tail(element: etree._Element) -> None:
     """删除噪声子树，同时把 tail 归还到相邻文本位置。"""
     parent = element.getparent()
diff --git a/tests/unittest/test_flash_html.py b/tests/unittest/test_flash_html.py
index dcaebd81..57d4b3d2 100644
--- a/tests/unittest/test_flash_html.py
+++ b/tests/unittest/test_flash_html.py
@@ -500,6 +500,28 @@ def test_html_auto_selection_precomputes_nested_subtree_penalties(monkeypatch: p
     assert normalization_calls < leaf_count * 8
 
 
+def test_html_soft_prune_precomputes_deep_subtree_text(monkeypatch: pytest.MonkeyPatch) -> None:
+    """验证 soft prune 只线性扫描深层候选中的大段文本。"""
+    depth = 200
+    text = "x" * 4096
+    root = lxml_html.fromstring("<main>" + "<div>" * depth + f"<p>{text}</p>" + "</div>" * depth + "</main>")
+    original_normalized_text = html_selector_module._normalized_text
+    normalized_input_chars = 0
+
+    def counted_normalized_text(value: str | None) -> str:
+        """累计送入文本规范化函数的原始字符数。"""
+        nonlocal normalized_input_chars
+        normalized_input_chars += len(value or "")
+        return original_normalized_text(value)
+
+    monkeypatch.setattr(html_selector_module, "_normalized_text", counted_normalized_text)
+
+    html_selector_module._soft_prune(root)
+
+    assert normalized_input_chars <= len(text) * 2
+    assert text in "".join(root.itertext())
+
+
 def test_html_referenced_external_footnote_keeps_anchor_and_content() -> None:
     """验证正文候选外但被引用的 HTML footnote 会追加并生成可兑现 anchor。"""
     payload = b"""<html><body><article><h1>Notes</h1>
@@ -1277,6 +1299,16 @@ def test_html_comments_count_toward_dom_node_budget(monkeypatch: pytest.MonkeyPa
         doc_analyze(b"<html><body><!--1--><!--2--><!--3--></body></html>", file_suffix="html")
 
 
+@pytest.mark.parametrize("container", ["template", "form"])
+def test_html_ignores_stylesheets_beneath_discarded_active_subtrees(container: str) -> None:
+    """验证待删除活动子树内的 stylesheet 不会污染正文样式。"""
+    payload = f"<html><body><{container}><style>p{{display:none}}</style></{container}><p>Visible</p></body></html>".encode()
+
+    markdown = render_markdown(doc_analyze(payload, file_suffix="html")[0])
+
+    assert "Visible" in markdown
+
+
 @pytest.mark.parametrize(
     ("styles", "single_limit", "total_limit", "expected_limit"),
     [