| Si Yajie | |
| Native Name: | 司雅杰 |
| Native Name Lang: | Chinese |
| Nationality: | Chinese |
| Birth Date: | 4 December 1998 |
| Birth Place: | Xi'an, China |
| Height: | 1.64 m |
| Weight: | 57 kg |
| Country: | China |
| Sport: | Diving |
| Event: | 10 m |
| Club: | Shaanxi Province |
Si Yajie (; born 4 December 1998) is a Chinese female diver. As a 14-year-old, she won the gold medal in the women's 10 m platform at the 2013 World Aquatics Championships.[1]