Tang Xin joined
Beijing Guoan's youth academy at the age of twelve along with twin younger brother
Tang Miao in 2002. He was registered with
China League Two side
Liaoning Zhongba for the 2006 season. He was loaned to Beijing Guoan's satellite team
Beijing Guoan Talent, which would play as a foreign team in Singapore's
S. League in the 2010 season. Tang was on the bench for most time of the season. On 27 September 2010, he made his senior debut against
Gombak United, coming on for
Li Tixiang in the half time, as the result that some Beijing players was banned for participating a brawl in a league match against
Young Lions. Tang scored his first goal in the match, which resulted in a 1–1 draw. He was released by Beijing Guoan at the end of the season. Tang joined China League Two side
Jiangxi Liansheng in 2012 after he recovered from ankle surgery. Tang received a trial with
Guangzhou R&F at the recommendation of Tang Miao, whom played as a regular right-back at the club, and joined R&F's reserved team in 2014. He played 23 matches in the 2016 season as Guizhou Zhicheng finished the runners-up of the league and won promotion to
Chinese Super League. On 28 April 2017, he made his Super League debut in a 3–1 away victory against Guangzhou R&F, contesting with Tang Miao. The match marked the first time twin brothers had played for opposing teams in the Chinese Super League. After having spent five seasons at Guizhou and playing over 100 games for them, Tang would join
Chengdu Rongcheng on 12 April 2021 on a free transfer. He made his debut for the club in a league game on 21 September 2021 against
Beijing Institute of Technology in a 2-0 victory. He would establish himself as a regular within the team and aid the club to promotion to the top tier at the end of the
2021 league campaign. On 19 January 2026, the club announced his departure after the 2025 season. ==Career statistics==