I am F-1 visa holder, working on my OPT. My sister is also on F-1 visa and I am sponsoring her education. Can I claim her tuition as deduction while filing my tax return?

When did you first come to the US?

I came to US in Dec 2013. Started my Masters in Jan 2014. Graduated Dec 2015 and working since then. My sister came to US in Dec 2016, she started her Masters in Jan 2017.

As a F-visa holder, you are considered as a nonresident for five years from the year you first enter the US.  In your situation, it is from 2013-2017.  As a nonresident, you are not allowed to claim any education credit or deduction on your 2017 taxes.  Starting from January 1, 2018, you might be treated as a resident for tax purposes on your 2018 taxes if meet the Substantial Presence Test SPT.  In order to claim your sister's expenses you paid, she has to qualify to be your dependent on your taxes. To qualify as a dependent, she has to meet all the following rules:

• She has to be either a US resident or resident of Canada or Mexico. 
• Gross Income: She earned less than $4,050 in 2017.
• Total Support: You provide more than half of her total support for the year. -Please see Support Test
• Relationship:  She is related to you.  See  Qualifying relative Relationship
• She cannot be claimed by another taxpayer. 

Since she carries a F-visa as a nonresident, she likely does not qualify as your dependent.