RESUMO
At present, China's medical service costs keep rising, and residents' out-of-pocket medical expen-ses are also increasing heavily. The prepayment reform of medical insurance is considered as an important starting point to solve the problem. It is of great significance to evaluate the effect of prepaid medical insurance reform on con-trolling medical expenses and reducing economic burden when sick. In order to achieve the objective of this study, a use of CHARLS data 2011 &2015 and DIDPSM theory, and a combination of the Interaction Item Model and PSM model, and make use of a natural experiment developed from experimental reform stage for the comprehensive promo-tion stage of new rural cooperative medical system (NCMS) in 2012, were very crucial. This paper finds that:(1) Prepayment system can control the rise in outpatient and inpatient expenses. Compared with those who did not partici-pate in NCMS in the initial stage of reform, after the universal reform, outpatient and inpatient expenses dropped by 6. 3％ and 41％, the average decrease was 1041yuan and 2895yuan, respectively. (2) After the universal reform, the insured patients' medical burden of outpatient and inpatient reduced by 17％ and 33％. Prepayment system has, to some extent, resisted the rise in medical expense, and alleviated the burden of medical treatment. (3) On the basis of PSM, the estimated value and significance of coefficients have not changed, the effect of PPS reform is good. The poli-cy implication is that accelerating the prepayment system reform is the key way to control the growing medical expenses.