With the increasing aging of the population, the increase of the disabled population and the disorder expansion of medical expenses threaten the sustainable development of the medical security system. We based on the China Health and Retirement Longitudinal Study in 2011, 2013, 2015, and 2018, this study used the Differences-in-Difference method to explore the effect of long-term care insurance on outpatient utilization and medical expenses. The results show that long-term care insurance can significantly reduce out-of-pocket medical expenses and outpatient visits. The heterogeneity analysis showed that long-term care insurance had a more significant impact on the medical insurance participants of urban and rural residents than the medical insurance participants of urban workers. At the income level, long-term care insurance reduced medical costs for middle - and upper-income families but had little effect on low-income families. These conclusions verify the value of long-term care insurance and provide a valuable reference for the new round of medical reform and the expansion of pilot scope in China.