The red soil region of southern China is an important agricultural production base because it is rich in water, heat resources, and has an excellent social location. However, the long-term and intensive farming, the large slope of hills and the concentrated and strong precipitation trigger many environmental problems such as the ecological function degradation, which threatens the food and ecological security. Therefore, it is urgent to study the changes of ecosystem services in the region. This paper used the Carnegie Ames-Stanford Approach (CASA) model, InVEST model, and RUSLE to quantitatively evaluate the Net Primary Productivity (NPP), Crop Production (CP), Soil Conservation (SC), and Water Yield (WY) in the red region of southern China before and after Grain-for-Green Project (GTGP). The temporal and spatial characteristics of tradeoffs and synergies among different ecosystem services were discussed using partial correlation analysis and spatial autocorrelation analysis. The effect of GTGP on the relationships among various ecosystem services was determined. The results showed that:(1) after GTGP, NPP, CP, SC and WY in the red soil region of southern China all increased overall, but some areas still presented a weakening trend. The NPP indicated a weakening trend in the south, SC showed a weakening trend in the northeast, and both CP and WY showed a weakening trend in the southeast coast. (2) After GTGP, the relationship between NPP and WY changed from very significant synergies (r=0.315, P=0.025) to significant tradeoffs (r=-0.279, P=0.059); no significant synergies relationship between SC and WY changed to significant tradeoffs (r=-0.427, P=0.024); the rest of the relationship of ecosystem services has not changed much. (3) Before and after GTGP, the distribution pattern of NPP, CP, and SC did not change significantly, and the distribution pattern of WY changed dramatically with significant increase in Northeast and Southwest. (4) Spatially, the trade-offs and synergies among the four ecosystem services were significantly heterogeneous. The Moran's I index of the CP-SC was the smallest (0.012), and the Moran's I index of the NPP-SC and NPP-WY were all greater than 0.7, all other Moran's I index are greater than 0. The results of this article are conducive to the depth understanding the impact of GTGP on the spatial and temporal changes of ecosystem services, and provide a scientific basis of determine the development direction of ecological agriculture, forestry and animal husbandry in vulnerable ecologically areas and the optimization of ecosystem services for sustainable development in the red soil region of southern China.