diff --git a/docs/guidance/usage.md b/docs/guidance/usage.md
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+<!--
+ * @FilePath: \SimSwap\docs\guidance\usage.md
+ * @Author: AceSix
+ * @Date: 2021-06-28 10:01:40
+ * @LastEditors: AceSix
+ * @LastEditTime: 2021-06-28 10:03:49
+ * Copyright (C) 2021 SJTU. All rights reserved.
+-->
 
 # Usage
 
+###### Before running, please make sure you have installed the environment and downloaded requested files according to the [preparation guidance](docs/guidance/preparation.md).
+
 ### Simple face swapping for already face-aligned images
 ```
 python test_one_image.py --isTrain false  --name people --Arc_path arcface_model/arcface_checkpoint.tar --pic_a_path crop_224/6.jpg --pic_b_path crop_224/ds.jpg --output_path output/