Using Ashare listed companies in Chinas securities market from 2004 to 2021, this paper examines the relationship between entrepreneurs positionholdings in commerce chambers and the agency cost of enterprises, and further examines the potential impact of personal reputation mechanism on the above relationship. The results indicate that: entrepreneurs positionholdings in commerce chambers can significantly reduce the first kind of agency cost between shareholders and managers and the second kind of agency cost between controlling shareholders and minority shareholders, and the higher the regional level of the chamber of commerce and the more types of the chamber of commerce, the more significant this effect is; When a firm has the political identity of a National Peoples Congress representative or a member of the Chinese Peoples Political Consultative Conference, as well as the social identity of a parttime listed firm, the inhibitory effect of the chamber of commerce relationship on the agency cost of the firm is relatively weak; The channel inspection found that the incentive mechanism and supervision mechanism of enterprises are important channels for the relationship between entrepreneurs and chambers of commerce to affect the agency cost of enterprises; Further analysis reveals that the relationship between entrepreneur industry associations and national and provincial chambers of commerce has a more significant inhibitory effect on agency costs, while the relationship between entrepreneur chambers of commerce has a more significant inhibitory effect on agency costs in nonstateowned enterprises. This study reveals for the first time that the relationship between entrepreneurs and chambers of commerce under the constraint of collective reputation can effectively reduce corporate agency costs, but the entrepreneurs personal reputation mechanism has a certain substitute for the collective reputation mechanism formed by participating in the chamber of commerce. The research provides a new theoretical analysis framework and empirical evidence for the indepth understanding of the countrys unique chamber of commerce relational culture on the regulation of economic development.