diff --git a/head_extension_app.py b/head_extension_app.py
index 83ceff0..4743011 100644
--- a/head_extension_app.py
+++ b/head_extension_app.py
@@ -119,6 +119,28 @@ def crop_head_neck(image):
     return image.crop((left, top, right, bottom))
 
 
+def cutoff_center_z(coordinates_cutoff):
+    return float(np.mean([point[0] for point in coordinates_cutoff]))
+
+
+def draw_cutoff_line(panel, image_depth, coordinates_cutoff=DEFAULT_COORDINATES_CUTOFF):
+    panel = panel.copy()
+    crop_height = int(image_depth * 0.72)
+    if crop_height <= 0:
+        return panel
+
+    line_y = int(round((image_depth - 1 - cutoff_center_z(coordinates_cutoff)) * panel.height / crop_height))
+    if line_y < 0 or line_y >= panel.height:
+        return panel
+
+    draw = ImageDraw.Draw(panel)
+    shadow = (0, 0, 0)
+    line_color = (255, 215, 60)
+    draw.line((0, line_y, panel.width, line_y), fill=shadow, width=6)
+    draw.line((0, line_y, panel.width, line_y), fill=line_color, width=3)
+    return panel
+
+
 def fit_image(image, width, height):
     scale = min(width / image.width, height / image.height)
     resized = image.resize(
@@ -333,12 +355,18 @@ def run_deformation(input_dir, output_dir, angle_degrees, transition_width, prog
     output_paths["legacy_soft"] = legacy_soft_dir
 
     progress("正在生成四状态过程对比图...")
-    preview_paths = make_four_state_preview(state_images, Path(output_dir), angle_degrees)
+    preview_paths = make_four_state_preview(
+        state_images,
+        Path(output_dir),
+        angle_degrees,
+        vol_info.coordinates_cutoff,
+    )
     make_output_preview_from_images(
         state_images["original"],
         state_images["soft_transition"],
         Path(output_dir),
         angle_degrees,
+        vol_info.coordinates_cutoff,
     )
     return output_paths, preview_paths
 
@@ -375,14 +403,17 @@ def make_output_preview(original_dir, deformed_dicom_dir, output_dir, angle_degr
     return preview_path
 
 
-def sitk_sagittal_panel(image):
+def sitk_sagittal_panel(image, coordinates_cutoff=None):
     volume = sitk.GetArrayFromImage(image)[::-1]
-    return crop_head_neck(sagittal_mip(volume))
+    panel = crop_head_neck(sagittal_mip(volume))
+    if coordinates_cutoff is not None:
+        panel = draw_cutoff_line(panel, volume.shape[0], coordinates_cutoff)
+    return panel
 
 
-def make_output_preview_from_images(original_image, deformed_image, output_dir, angle_degrees):
-    before = sitk_sagittal_panel(original_image)
-    after = sitk_sagittal_panel(deformed_image)
+def make_output_preview_from_images(original_image, deformed_image, output_dir, angle_degrees, coordinates_cutoff=None):
+    before = sitk_sagittal_panel(original_image, coordinates_cutoff)
+    after = sitk_sagittal_panel(deformed_image, coordinates_cutoff)
 
     slide = Image.new("RGB", (2560, 1440), (0, 0, 0))
     draw = ImageDraw.Draw(slide)
@@ -408,14 +439,14 @@ def make_output_preview_from_images(original_image, deformed_image, output_dir,
     return preview_path
 
 
-def make_four_state_preview(state_images, output_dir, angle_degrees):
+def make_four_state_preview(state_images, output_dir, angle_degrees, coordinates_cutoff=None):
     output_dir = Path(output_dir)
     screenshot_dir = output_dir / "process_screenshots"
     reset_folder(screenshot_dir)
 
     panels = []
     for state_key, label, _ in STATE_LABELS:
-        panel = sitk_sagittal_panel(state_images[state_key])
+        panel = sitk_sagittal_panel(state_images[state_key], coordinates_cutoff)
         panel_path = screenshot_dir / f"{state_key}.png"
         panel.save(panel_path, quality=95)
         panels.append((label, panel))
@@ -573,6 +604,7 @@ class HeadExtensionApp:
                 self.status.set("正在读取 DICOM 生成预览...")
                 self.cached_volume = load_dicom_volume(self.input_dir.get())
             before = crop_head_neck(sagittal_mip(self.cached_volume))
+            before = draw_cutoff_line(before, self.cached_volume.shape[0])
             after = preview_deform_2d(before, float(self.angle.get()))
 
             canvas = Image.new("RGB", (1120, 610), (0, 0, 0))
diff --git a/web_backend.py b/web_backend.py
index ec3e8de..e6e97a0 100644
--- a/web_backend.py
+++ b/web_backend.py
@@ -25,6 +25,7 @@ from head_extension_app import (
     APP_DIR,
     crop_head_neck,
     ct_window,
+    draw_cutoff_line,
     fit_image,
     load_dicom_volume,
     preview_deform_2d,
@@ -549,6 +550,7 @@ def start_job(kind, worker, owner=None, params=None, remember_user_task=True):
 def make_preview(input_dir, angle_degrees):
     volume = load_dicom_volume(input_dir)
     before = crop_head_neck(sagittal_mip(volume))
+    before = draw_cutoff_line(before, volume.shape[0])
     after = preview_deform_2d(before, float(angle_degrees))
 
     canvas = BytesIO()