Tan Sixin (Chinese: 谭思欣; pinyin: Tán Sì Xīn, born January 10, 1995, in Jiangmen, Guangdong) is a female Chinese gymnast.

At age 14, she won the beam final in the 2009 National Games of China beating Olympians including World Champion Deng Linlin.

At the Youth Olympics in 2010, she won Gold in the Beam and Floor Exercise and Silver in the All-Around and Uneven Bars final (after Viktoria Komova).

However, multiple mistakes in the preliminary competition prevented her from entering the all-around and event finals.

She competed at the Individual National Championships finishing out of the medals in the uneven bars and balance beam, which many people consider her best events.