 Having known Xu from the time when Xu and Xiao Yi were friends, Emperor Wu made him a mid-level official.After the prime minister Fan Yun died in 503, Emperor Wu entrusted the important matters of state to Xu and Zhou She, effectively making them co-prime ministers, even though neither carried the title and neither received particularly high rank.As de facto prime minister, Xu was considered to be capable, diligent, and honest.