Abstract: According to the investigation, the factors that promote the participation of patients in the first diagnosis at the primarylevel include the convenience and rapidness of the first diagnosis at the basic level, the application of the first diagnosis to common diseases, the good communication between doctors and patients and the money saving.The factors that hinder patients' participation in primary care include inherent cognition, professional competence of community hospitals, basic conditions and referral procedures. On the basis of qualitative research, this paper analyzes the problems existing in the primary diagnosis process of graded diagnosis and treatment with the relevant theories of public economics, and finds that the value selection, interest game, monopoly and externality of utility will seriously affect the extensive implementation of graded diagnosis and treatment. Therefore, it is urgent for the government to strengthen regulation to curb externalities and improve the comprehensive level of medical services in primary medical institutions.