"New Years Eve Party" if you're talking about the parties that happen on January 31.

EDIT: If you wanted to title a new years eve party (like give it a name in Facebook or something), you could title it "End of the Year Party"

Like OOPT said, if it's a company party they might want to be sensitive to people's religion or culture.  Some people don't celebrate Christmas or Hanukkah, two major holidays that are in these time period.  So they might call it a Holiday Party (that's what my company calls it).  If it's December 31st, it would be a New Year's Eve Party.  You would not have a New Year's Eve party before December 31st.

So, I think you're looking for "New Year's Eve Party", given that you specifically mention 1/1/2017.

Note: I just realized I said January 31st in my comment above.  I meant December 31st, or before January 1st.

It depends on where you audience is from. In the USA, it also depends on which political affiliation your guests might have.

So you might call it a

Christmas Party (Traditional)

Holiday Party

End of Year Party

(A recent new one I read about) End of Fiscal Year Party

Anyway some people have so much time on their hands, they figure how to make simple things very complicated.

Thank you so much OOPT, Steven. Your anwers is much valuable to me. I will keep in mind that always make simple things and I will use "New Year's Eve Party" for Januaray 1, 2017. Thank you so much!

so thanks,

I am talking about the party that every company will make before 2017 ( 1-1-2017).

@Steven: do you know the name of the party that i want to talk about?