Abstract: Farmers cooperatives can play an important role in the control of the quality and safety of agricultural products. While the result of quality control of agricultural products will be influenced significantly by the scales and governance mechanisms of farmers cooperatives. Based on the theory of collective action and assuming the process of quality control of cooperatives being a result of the collective actions of the cooperatives, this paper analyzed the relationship between the scales of the cooperatives and the quality control of agricultural products, and explored the internal governance mechanisms of the cooperatives based on the quality control of agricultural products. Results show that the cooperatives should maintain a proper scale in order to achieve economies of scale, and enhance the power of farmers to produce high quality agricultural products through more patronage dividend. However, it is not conducive to the quality control of agricultural products if the scales of cooperatives are too large. At the same time, farmers cooperatives should construct its internal governance mechanism based on the quality control of agricultural products, which includes implementing membership management to control the scale of cooperatives, improving the exit management of cooperatives based on the quality control of agricultural products, designing the reasonable constraint mechanism for the production behaviors of farmers, and enhancing the exclusive attribute and the ability of quality premium of agricultural products from farmers cooperatives. Furtherly, this paper provides the following suggestions to implement the scale control of cooperatives effectively and to improve the capacity to control the quality and safety of agricultural products: 1) improving the internal governance structure and strengthening the authority and management ability of the council of cooperatives; 2) enhancing the industrial policy support for the development of cooperatives.