diff --git a/tools/generate.py b/tools/generate.py
index e70df69..567c538 100644
--- a/tools/generate.py
+++ b/tools/generate.py
@@ -70,7 +70,11 @@ def generate(args):
         cfg_scale = args.cfg_scale
         model = UNet(num_classes=num_classes, device=device, image_size=image_size, act=act).to(device)
         load_model_weight_initializer(model=model, weight_path=weight_path, device=device, is_train=False)
-        y = torch.Tensor([class_name] * num_images).long().to(device)
+        if class_name == -1:
+            y = torch.arange(num_classes).long().to(device)
+            num_images = num_classes
+        else:
+            y = torch.Tensor([class_name] * num_images).long().to(device)
         x = diffusion.sample(model=model, n=num_images, labels=y, cfg_scale=cfg_scale)
     else:
         model = UNet(device=device, image_size=image_size, act=act).to(device)
@@ -97,6 +101,7 @@ def generate(args):
     # Input image size (required)
     parser.add_argument("--image_size", type=int, default=64)
     # Number of generation images (required)
+    # if class name is `-1` and conditional `is` True, the model would output one image per class.
     parser.add_argument("--num_images", type=int, default=8)
     # Weight path (required)
     parser.add_argument("--weight_path", type=str, default="/your/path/Defect-Diffusion-Model/weight/model.pt")
@@ -119,6 +124,7 @@ def generate(args):
     # Number of classes (required)
     parser.add_argument("--num_classes", type=int, default=10)
     # Class name (required)
+    # if class name is `-1`, the model would output one image per class.
     parser.add_argument("--class_name", type=int, default=0)
     # classifier-free guidance interpolation weight, users can better generate model effect (recommend)
     parser.add_argument("--cfg_scale", type=int, default=3)