Short answer, no.
You cannot save any version to an earlier version. If you have SW2016 SP5 you may be open the SW2017 file with the possibility that some of the features may not solve correctly.
Otherwise, you can save the SW2017 in some neutral format (STEP, etc) and open that in SW2016.
If you are dealing with Part file try to convert SW to Parasolid binary, open it in SW 2016 and use Feature Recognition to recreate original model.
Wonder why you want to do that 017 marketeers claim its a major improvement ,
As many others are pointing out SOLIDWORKS itself does not have the ability to save into past version files. There are some interesting solutions to this floating around the internet like this one (BackWorks for SOLIDWORKS) which (sort of) reconstructs your newer version files in a past version file format.
BackWorks works for the most part (a good proof of concept) but is very slow and it uses a decent amount of CPU. It’s not something you want to use on a complex part without dedicating another machine to do the job. It has buggy error reporting and does crash. It also prompts on failed features (to continue or not) which probably means you will have to monitor progress instead of just leave it and come back in 30 minutes to your finished backward converted file.
I hear BackWorks 2017 is supposed to be a ground-up recode based on the lessons learned in the current version so it likely will get better.