In 2003, author and TV Producer Hai Yan selected her for the female lead in the television series Goddess of Mercy. Sun received overwhelmingly positive feedback from audiences for her portrayal of An Xin, and rose to fame in China as one of the most promising young actresses. In an interview with Global Times, Sun thanked Ding Hei, the Director of Goddess of Mercy saying; "Not only because he provided me with [the role of] An Xin, but what's more, he believed in me, a person who never received any formal acting lessons. ... It benefited me all my life."