File "D:\Python深度学习\Pytorch\YOLO\test_code\yolov5-master\val.py", line 38, in <module> from models.common import DetectMultiBackend

This error occurs because the Python interpreter cannot find the module "models.common" that is being imported in the "val.py" file.

One possible solution is to make sure that the "models" directory is in the Python path. You can add the path to the "models" directory to the PYTHONPATH environment variable or use the sys.path.append() function to add the path to the Python path within your script.

Another possible solution is to check if the "models" directory is present in the current working directory. If it is not present, you can download or clone the repository that contains the "models" directory and place it in the correct location.