Sima Maoying was a daughter of Emperor Gong and his wife, Chu Lingyuan.
She must have been created princess during her father's brief reign (419–420), and it was also at that time that she married Liu Yifu (the future Emperor Shao), then the heir apparent to the powerful general Liu Yu (the future Emperor Wu of Song).
In 420, her father-in-law forced her father to yield the throne to him, ending Jin and establishing Liu Song.
However, in 424, officials whom Liu Yu had left in control of the government deposed Emperor Shao, believing him to be unfit to be emperor, demoting him to the title of Prince of Yingyang (营阳王).
The former Empress Sima therefore carried the title Princess Dowager of Nanfeng.