Entrepreneurship formalization is an effective way to promote the integration of farmers’ entrepreneurship into modern agricultural industry and create economies of scale， and is also an important basis for rural revitalization and common prosperity. Most of the existing studies explore farmers’ entrepreneurship formalization from the perspective of formal institutions， ignoring the role of informal institutions， such as clan culture， on farmers’ entrepreneurship formalization. Based on the institutional theory， it employed the number of regional family genealogies as a proxy for clan culture，investigated the impact of clan culture on the formalization of farmers’ entrepreneurship. Furthermore， it analyzed the influence mechanism of clan culture on this formalization process via the mediating roles of in-group/out-group social trust and the moderating role of digitalization levels. The results are as following. First， clan culture inhibits farmers’ entrepreneurship formalization. Second， in-group trust and out-group trust play mediating roles in the relationship between clan culture and farmers’ entrepreneurship formalization. Furthermore， digitalization weakens the inhibitory effect of clan culture on farmers’ entrepreneurship formalization. The findings expand the theoretical cognition of the entrepreneurship formalization from the perspective of informal institutions， and provide significant guidance for farmers’ entrepreneurship and rural revitalization.