This paper, based on the data of Chinese family farms from 2013 to 2021, uses the transformation of rural credit cooperatives (RCCs) into rural commercial banks (RCBs) as a quasi-natural experiment and employs a multi-period gradual Difference-in-Differences (DID) model to empirically test the impact of the commercialization reform of RCCs on the growth of family farms and its mechanisms. The study finds that: (1) the commercialization reform of RCCs significantly promotes the growth of family farms; (2) in terms of mechanisms, the commercialization reform of RCCs can promote the growth of fam...