From the description of Dtls library, it seems it's not available in python3. And when I want to install with pip install Dtls there's always an 
Command "python setup.py egg_info" failed with error code 1 in C:\Users\sun\AppData\Local\Temp\pip-build-c_46y9mt\Dtls\
Solution here doesn't help. I am using Python 3.6 on Win7. Do I have another option for DTLS?
                        
If the library you want to use is not available for the version of your interpreter, then you simply cannot use that library without porting it yourself or waiting for others doing that for you. This is probably not what you want.
This means that
Dtlslibrary works only for Python2.7 and version 1.0.0 or higher of the OpenSSL library as mentioned on the website, although it's tested on several plattforms (including yours):You can use other libraries if you have to use Python3.x, e.g. standard
ssllibrary or maybe also pyOpenSSL library:Dtlsis a library which simplifies implementation but you are not dependent on it. Just as a side note: For pyOpenSSL you can also get an idea how to implement it by reading this post.