OBJECTIVE： To provide reference for medical costs control in China. METHODS： Based on main characteristics of the United States health service system， information asymmetry， principal-agent theory and Freedman’s consumption theory were used to analyze the advantages of restrictive relationship among doctors， hospitals and health insurance institutions in controlling medical costs and improving the quality of diagnosis and treatment. The growth rate of medical cost， the percentage of drug expenditure and other aspects were compared between China and the United States； the effect of restrictive relationship on medical cost control was demonstrated. RESULTS & CONCLUSIONS： In the United States， there are hierarchical medical system and two-way referral system； for-profit hospitals and non-profit hospitals are mutually complementary； different natures of health insurance system， different payment methods and strict “commercial bribe” monitoring system are carried out； doctors， hospitals and health insurance restrict each other. Not only there are many advantages in theory， but also in practice the growth rate of medical cost and the percentage of drug expenditure are superior to our country. Finally it controls the rapid growth of medical cost to a certain extent. Combined with our national conditions， learning from the United States experience， restrictive relationship among doctors， hospitals and health insurance institutions is established to control the increase of medical cost in China through reducing information asymmetry and standardizing payment audit； establishing a scientific pattern of mixed payment； strengthening the indirect impact of the health insurance institutions on doctors and hospitals， etc.