Sun Jiajun (Chinese: 孙佳俊, born 1 August 2000) is a Chinese swimmer.^[2] He won the gold medal in the boys' 100-metre breaststroke and 4 × 100-metre mixed medley relay events at the 2018 Summer Youth Olympics held in Buenos Aires, Argentina. He also won the silver medal in the boys' 50-metre breaststroke and 4 × 100-metre medley relay categories in the same event.^[3][4] In 2021, he qualified to represent China in the men's 4 × 100-metre medley relay event at the 2020 Summer Olympics held in Tokyo, Japan.^[2]

• List of Youth Olympic Games gold medalists who won Olympic gold medals

• Sun Jiajun at World Aquatics
• Sun Jiajun at Olympics.com
• Sun Jiajun at Olympedia
• Sun Jiajun at the Paris 2024 Summer Olympics