At the 2019 IAAF World Relays, Su raced with his teammates Wu Zhiqiang, Xie Zhenye and Liang Jinsheng in the 4 × 100 metres relay. Running the third leg, Su aided his teammates to a second-place finish in the heats, qualifying them for the final with a time of 38.51 seconds. In the final, the Chinese team crossed the line in a season's best 38.16 seconds, subsequently missing out on a bronze medal finish by just 0.01 seconds.