Cai Zelin (, born 11 April 1991, in Huize, Yunnan) is a Chinese male racewalker. He finished 4th at the 20 km walk during the 2012 London Olympics, and won the silver medal at the 2016 Rio Olympics. He finished 5th at the 2015 World Championships in the 20 km race walk. In 2019, he competed in the men's 20 kilometres walk at the 2019 World Athletics Championships held in Doha, Qatar. He did not finish his race.