The modernization of rural governance has promoted the transformation of the channels for farmers to express their interest demands from non-institutionalization to institutionalization. Existing studies focus on the non-institutionalized expression of interests of farmers, and ignore the types of institutionalized actions and their processes. This paper explores the process and logic of farmers' institutionalized expression of interests through a comparative analysis of different types of cases based on the survey of petition governance in Shui town in western Sichuan. It is found that in the process of institutionalized interest expression, farmers create the identity qualification, invisible rights and interests, and action space required for institutionalized interest expression through such action tools as role shaping, memory narrative, and institutional support, based on the action of social recognition, emotional identity, and institutional opportunity within the institutional space, which constitute the action process of farmers' institutionalized interest expression. These constitute the action process of farmers' institutionalized interest expression. Finding a favorable “institutional position” is the logic of action for the expression of institutionalized interests. It is the position and space for the development of the actors in the institutional structure of a specific field, which provides favorable resources, conditions, and opportunities for farmers' actions, and complements the theoretical explanation of “tool-action” with process and mobility. Identifying the respective institutional positions of the government and farmers in grassroots governance will help to resolve conflicts and enhance the effectiveness of governance.