Objective：This study aimed to evaluate the impacts of the “ fix out of pocket” payment policy on inpatients visits and medical expense s per visit for New Rural Cooperative Medical System(NRCMS) and to examine whether the medical insurance payment change could really solve the problem of difficulties and high costs of receiving medical services or not in rural Hainan, China; Methods: Using descriptive analysis, difference in difference (DID) model based on data from Wanning county where the new policy has been carried out, Ledong county where has not, including claim data, medical records and hospital utilization data from Nov 2010 to Oct 2014. We also supplemented and interpreted the results of quantitative analysis combined with qualitative data from the interview recording material; Results: The policy may increase the number of inpatient visits, but had limited effect on keeping patients in primary medical institutions. The policy reduced the average medical expenses per inpatient visit at township hospitals on the whole . As for the two most common hospitalized diseases(hypertension and pneumonia), from DID model, the policy increased out of pocket(OOP) in Wanning by 11% and 28% respectively. As for the allocation of NRCMS fund, there is no significant influence; Conclusion: The “fix out of pocket” policy can reduce the hospitalization cost per visit at township hospital on the whole, but may neither increase the utilization of inpatient services nor rationalize the use of NRCMS fund. The impacts for patients’ payment differ in different areas. For mild cases, it may increase OOP and length of stay