There are trade-off and synergy relationships among multiple ecosystem services under the influence of social, economic, and environmental factors. Identifying the relationships and clarifying their spatial and temporal features and driving forces can enhance multiple ecosystem services and promote integrated ecosystem management. However, the research is still in its infancy. The relationships of ecosystem services cannot be effectively revealed due to a lack of quantitative methods and data samples. Moreover, most studies on driving mechanisms are limited to one or several specific factors, while short of comprehensive factor analysis and dominant factor identification. In this study, the Taihu Basin in Jiangsu Province was taken as an example due to its special social-economic status, as well as notable nonpoint source pollution problem. Nitrogen purification, phosphorus purification, water supply, and soil retention services were selected according to the ecological context of the study area. Spatially explicit biophysical models and empirical statistical models were used to quantify and map indicators of four ecosystem services. The trade-off and synergy relationships of ecosystem services were expressed by GIS spatial analysis methods. Thirty-one driving forces were chosen in view of data availability and expert knowledge. Multiple logistic regression models were applied to identify the dominant driving forces based on the spatial quantification of ecosystem service relationships and driving forces. The results indicate that 1) from 2000 to 2010, the annual average nitrogen export per area increased first and then decreased slightly, the annual average phosphorus export per area gradually increased, the annual average water supply service per area decreased first and then increased, and the annual average soil retention service per area gradually decreased. There were distinct differences in the spatial patterns of the four ecosystem services. 2) Both the same and opposite changed areas of the relationship between nutrient exports and water supply were widely distributed, which indicated that the trade-off and synergy relationships between the nutrient purification services and water supply service were conspicuous. While the widest distribution area of the relationship between nutrient exports and soil retention services was showed that their relationship were not distinct. The relationship between nitrogen and phosphorus exports was showed mainly to be a positively changed area, which indicated a synergy relationship between these two services. 3) The dominant positive driving forces of relationship between nitrogen purification and water supply services were densities of urban construction and rural residential lands, in which an increment of 1 hm²/km² would promote the occurrence probability of this relationship to enhance by 29.100 and 10.282 times, respectively. Both the vegetation fraction and water network density had significant negative effects on the relationship between nitrogen purification and water supply services. The main influence factors of the relationship between nitrogen and phosphorus services were vegetation fraction, followed by the proportions of cultivated and forest lands; these factors mostly played positive roles.