The soil erosion in hilly red soil region (HRSR) of southern China has a serious impact on the local ecological environment. The government has implemented a series of ecological projects to control soil erosion. However, there are few studies on the ecological effects of ecological projects such as the Grain for Green Program (GFGP) in the southern region. This paper selected the hilly red soil region of southern China as the research area. Based on the land use data in 2000, 2005, 2010, and 2015, we identified the spatial extent of the Grain for Green Program (GFGP) in HRSR. We also estimated the effect of soil conservation in areas where the GFGP actually occurred by the Revised Universal Soil Loss Equation (RUSLE). The results showed that from 2000 to 2015, the GFGP area in the HRSR was about 2 052.61 km². During this period, soil conservation quantity increased by 918 million tons, and the change in soil retention per unit area was 447 327.54 t/km². The overall soil conservation effect was significantly improved, but some areas still had negative benefits. In addition, the conversion of bare land into forest land was the most effective way of land use change for improving soil conservation services. The implementation of GFGP improved the regional soil retention function. This study has guiding significance for the implementation and management of the GFGP in hilly red soil region of southern China.