After taking up the official post ,he did very well in managing the official business. He was courageous and resolute in handling cases, and punished according to law anybody who violated the law, no matter whether he was a despotic gentleman who was rich and powerful or was one of the common people.
When Yi Zong was transferred to be the prefect of the Nanyang Prefecture (南阳郡), Ning Cheng (宁成), a despotic landlord who stopped at nothing in doing evil, was living there，in order to ingratiate himself with Yi Zong, Ning Cheng pretended to be very modest and courteous every time he met Yi Zong and saw him off.
But Yi Zong had heard of the evil conducts of Ning Cheng already and, soon after he took office in Nanyang, he made investigations. It did not take much time for him to find out Ning cheng's crimes and had him put in prison.
Later, Emperor Wu Di (汉武帝) of the Han Dynasty appointed Yi Zong the prefect of the Dingxiang Prefecture (定襄).
At that time, the public order in Dingxiang was very chaotic. When he took office there, there were 200 convicts in prison who had committed felonies had no implements of punishment on them.There were also more than 200 persons who offered bribes in order to absolve those serious offenders from guilt.Yi Zong treated the matter severely. He arrested all those bribers and punished the bribers and those serious offenders already in prison severely. More than 400 convicts were executed in a day.
From that day on, whenever the name of Yi Zong was mentioned，people in Dingxiang would tremble with fear --they would shiver all over though not cold.