During the reign of Emperor Gaozong's wife Wu Zetian, Song Jing became "Fengge Sheren" (鳳閣舍人, "Fengge Sheren"), a mid-level official at the legislative bureau of government (鳳閣, "Fengge"). It was said that he acting properly while in office and was respected by Wu Zetian. In 703, when Wu Zetian's lovers Zhang Yizhi and Zhang Changzong tried to falsely accuse the chancellor Wei Yuanzhong by persuading Song's colleague Zhang Shuo to provide corroboration of their accusation that Wei wanted to pledge loyalty to Wu Zetian's son and crown prince Li Xian instead of Wu Zetian herself, it was Song, along with Zhang Tinggui () and Liu Zhiji who persuaded Zhang Shuo that historical reputation was more important than political expediency, which led Zhang Shuo to change his testimony and instead corroborate Wei's innocence. As a result, Wei (and Zhang Shuo) were exiled, but escaped death.