The choice of successors in family businesses has become one of the topics of concern in the theoretical and practical circles. This article selects the family companies listed in Shanghai and Shenzhen in 2008—2018 as the research object. From the perspective of audit costs, it analyzes the mechanism of professional managers' impact on audit fees, and examines the impact of family companies hiring professional managers on audit fees. Studies have shown that: Family companies that employ professional managers pay higher audit fees; there are both agency cost effects and reputation effects between the two, but agency cost plays a leading role, and reputation effects can suppress the increase in audit costs; further analysis found that family companies that employ professional managers have more serious agency problems and poorer internal control, and this is related to the senior management's tenure. The longer the professional manager's tenure, the better the internal control situation, but at the same time the agency conflicts also increase. Therefore, when choosing a professional manager as a successor, a family company should pay more attention to the agency problems it brings about, weigh the interests, and pay attention to the improvement and governance of the companys internal control.