how can i upgrade python3.5 to 3.6?

how can i upgrade python3.5 to 3.6?i flash my tx2 by jetpack3.3. the python is 3.5

I wonder if it is possible to upgrade to Python 3.7 on my TX2 with JetPack 3.3.

Should be able to follow any Ubuntu guide for compiling different Python versions. You might be able to find a PPA, but probably easier just to compile it from source at whichever version you need.

Try this:
https://solarianprogrammer.com/2017/06/30/building-python-ubuntu-wsl-debian/