Can I use script to render multiple frames by mental ray free in maya 2017?

Answer 1

If you're comfortable with the command line, then take a look at customizing the command line render string for Mental Ray. You should be able to apply the same method to 2017 assuming Mental Ray is installed and working properly. You can define frame ranges, individual frames, etc...

https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2016/ENU/Maya/files/GUID-FCB01DEF-10DF-4222-A047-AF0122782397-htm.html