OBJECTIVE：To study the cost control measures for Medicaid prescription drugs in the United States ，and to provide reference for medical insurance cost control in China. METHODS ：The policy documents ，academic papers and news reports were studied to comb the practice of drug cost control policy of Medicaid project in the United States and its impact on medical insurance costs. The suggestions were put forward for medical insurance cost control in China. RESULTS & CONCLUSIONS：The cost control measures of Medicaid prescription drugs adopted in the United States include drug utilization management and drug cost control measure. The former included the list of preferred drugs ，pre-authorization and step therapy ， prescription cost limit ，while the latter included the upper limit control of drug expenditure growth ，closed drug list management ， etc. The list of preferred drugs is the basis of a series of drug cost control measures ，which provides a policy framework for prior authorization and step therapy ；pre-authorization and step therapy are the specific ways to controlling the cost ，and the use of low-cost drugs is encouraged through the guidance of specific cases ；the prescription cost limit starts from controlling the drug cost of a single patient and saves the medical insurance expenditure from another angle ；the drug growth caps control is controlling the total cost of medical insurance expenditure from aspect of overall cost ，which is a supplement to the traditional method ；closed drug list management is a new policy attempt to break through the limitation of preferred drug list. The prescription drug cost control measures adopted by Medicaid project can effectively reduce the drug expenditure to a certain extent ，but it also has the possibility of harming the interests of patients because it can interfere with doctors ’prescription right. China should further strengthen the role of medical insurance in the medical service system ，and carefully learn from the management measures of Medicaid drug utilization in the United States ；improve the dynamic control mechanism of medical insurance expenditure ，take special measures for key drugs ； improve the drug list management mechanism ，pay attention to the three links of access， exit and dynamic adjustment ， guide medical cn institutions to use drugs rationally.