When he was young, Xu Mian became known for studiousness, and he was retained by Southern Qi's prime minister Wang Jian to serve as an assistant.
Around this time, Xu also befriended the army officer Xiao Yi (蕭懿), who later became a general.
As de facto prime minister, Xu was considered to be capable, diligent, and honest.
During his service, Xu also authored works designed to reestablish the formality of funeral mournings.
He died in 535, and both Emperor Wu and his crown prince Xiao Gang personally mourned Xu.