The impact of hydropower development on river ecosystems cannot be ignored, and scientific evaluation of its impact will contribute to the establishment of a more sustainable hydropower development patterns. In this paper, we analyzed the benefits and losses of the cascade hydropower development in the mainstream of the Wujiang River on the riparian terrestrial ecosystems and river ecosystems by using both equivalent factor and functional value evaluation methods. Based on the benefits and losses, we made a comprehensive evaluation of the cascade hydropower development on the river ecosystem services. The results show that the hydropower development in the mainstream of the Wujiang River increased the values of the riparian terrestrial ecosystem and river ecosystem services, particularly in the hydrological regulating and water supply functions. In addition, positive effects of the development were found on the power generation, hydrological and air regulating functions, while negative effects were observed on biodiversity maintaining and soil conservation. And the positive effects on river ecosystem service are greater than the negative effects. It was difficult to compare directly the ecological losses of unit electrical energy with other basins as different hydropower stations had their own emphasis regarding the positive and negative effects. Based on the long-term survey data of fish resources in the Wujiang River, the trend of fish biological loss index was analyzed to understand temporal cumulative ecological effects of hydropower development. The differences in the spatial pattern of hydropower generation were discussed by using InVEST model. The impact of ecosystem services such as biodiversity was hard to evaluate directly in terms of currency, and the service value per unit area of the water body was considerably higher than that of any other land-use types, which resulted in a conservative, e.g. a low value of negative effects of the hydropower development in the mainstream of the Wujiang River, and a high ratio of positive to negative values.