In order to investigate cumulative water environmental effects of construction of cascaded reservoirs on water environment comprehensively, new understandings of cumulative water environmental effects are summarized from the definition, classification, and characteristics. Common methods for investigating cumulative water environmental effects are compared. Research achievements of cumulative environmental effects of cascade development on runoff, water quality, water temperature, and sediment are reviewed from the aspects of influence scope and main characteristics. New tendencies for future study on the cumulative effects of cascaded reservoirs on water environment are discussed. It is concluded that the study on the cumulative effects of cascade reservoirs in China, mainly qualitative evaluation at present, is in a developing stage. It is necessary to establish a unified evaluation criteria and method in order to systematically investigate the environmental effects of the construction of cascaded reservoirs.