In 659, Xu was promoted to the post of deputy head of the examination bureau of government, and was also made a chancellor de facto.
[1] Late that year, he was made acting Shizhong (侍中): the head of the examination bureau and a post considered one for a chancellor by itself.
At some point, for the fact that he participated in editing imperial historical records, he was created the Duke of Ping'en.
Emperor Gaozong, in anger, stated, "Xu Yushi is a chancellor, but when the people's lives and properties were interfered with, he did not report to me.
Another chancellor, Xu Jingzong, who happened to be present, stated, "For an imperial subject to have this kind of attitude, death would be too good of a treatment for him!"
It was said that Xu governed Xiang Prefecture so well that both the people and his subordinates carved stone monuments to praise him.