Abstract: With the increasing roles of the united collaboration of farmer cooperatives during the process of agricultural modernization, it is of great significance to identify the united path for the benign development of the corporation. Based on the framework of system theory, taking the “Suhe” sales cooperation, the “Deng village” green tea corporation, and the “Longlian” corporation as examples, this paper analyzed the united paths of the cooperative service function system, and discussed the differences and similarities under different united paths. Results show that “further collaboration” between cooperatives will help to activate the complementarity and synergy among these cooperatives, to break the endowment constraints of the existing cooperative service ability, and to increase the utility of the cooperative economy of farmers. There are three kinds of united paths, including the service location, the service system, and the cross service system. Any single path has no advantages over the other, but the full play of the united utility needs to be a clear positioning to itself, and to match the members' ability and the perfect operation mode. In summary, different united paths apply to cooperatives of different sizes. This paper also provides the following policy suggestions: to encourage the strategic corporations for those relatively large cooperatives, to create product corporations for those middle sized cooperatives, and to build service corporations for those relatively small cooperatives.