If i open the jupyter lab in the Anaconda prompt the kernel can bu used. But when I use cmd to open selected file and open jupyter lab, the kernel can’t be used. This is so wired and I can’t figure out the reason
I’m not following what is the issue? You chose to use the Anaconda Distribution as your primary package manager. So now you have to use the routes described by Anaconda/conda to open Jupyter always. Anaconda/conda has complex handling of the way environments work and you have to get into those through activation of the environment first on the command line or Anaconda Navigator.
I think here describes the three ways you can start Jupyter in conjunction with Anaconda/conda. Do those work?
Yes, as you said. I haven’t activated the env in my cmd which lead to this problem. 
Thanks for your reply.