Abstract: In view of the dynamic change of competition relationship and its intensity among multiple objectives in different periods of basin water resources system scheduling process, a multi-objective time-varying-preference decision-making method is proposed. Taking the lower reaches of Jinshajiang River as an example, the spatiotemporal variabilities of power generation and ecological objectives are analyzed, and the Pareto frontier cluster of these two targets in chronological order is constructed and calculated. In addition, based on the non-dominated relationship of sensitivity ratio between targets, the objective preference of decision makers in each scheduling period is identified quantitatively to form the decision support set of bias degree, and a multi-objective time-varying decision-making model is established. The results show that there is a significant competitive relationship between cascade power generation and ecological objectives in the lower reaches of Jinshajiang River in normal flow year. The competition is the strongest in the refill period and weakest in the flood season; the competition intensity strengthens with the increase of power generation in each period. The time-varying-preference decision-making method, based on the physical basis of dynamic Pareto front, can significantly optimize the ecological benefits while maintaining the power generation benefits, and improve the guarantee degree of ecological demand in the critical period.