Under the realistic problem of moderately aging population and rising medical cost, long-term care insurance provides an opportunity to break this dilemma. Based on the data of China Health and Retirement Longitudinal Study (CHARLS) in 2011, 2013, 2015 and 2018, this paper analyzes the impact of the first batch of long-term care insurance pilot policies on the out-of-pocket medical expenses of target groups in pilot cities by using the method of Difference-in-Difference. The results showed that long-term care insurance significantly reduced out-of-pocket medical expenses for middle-aged and elderly people. The above empirical results have passed a series of robustness tests. Furthermore, the effect of long-term care insurance on reducing out-of-pocket medical costs is more significant in urban and western areas. The empirical results of this paper have certain practical significance for the extension of the pilot range of long-term care insurance and the improvement of the treatment design.