Abstract:Based on the questionnaire survey data of farmers’ professional cooperatives,the moderating effect of farm size on farmers’ trust is verified by hierarchical regression analysis.The result shows that farmers’ general trust and evaluation of the reputation of cooperatives on the promotion of cooperative performance are not affected by the regulation effect of farm size,and the promotion of farmer’s cognition and trust on cooperative performance is affected by the positive regulation effect of farm size.The result also shows that groups characterized with lower income,more external pressure,less revenue have a more obvious moderating effect.Therefore,this paper puts forward several suggestions,such as establishing a good contract environment,improving the stability of relational contracts between farmers and enhancing farmers’ cognition trust in cooperatives.The governments should actively guide the orderly transfer of rural land management right and encourage some farmer groups to moderately expand farm sizes through the transfer of land and other ways.