Aiming at the problem of the significant decline in source-load synchronization of a hydro-photovoltaic complementary system under the penetration of a high percentage of photovoltaic power generation, a nested scheduling model that couples long-term water storage regulation in the outer layer with short-term power complementary in the inner layer is constructed. The model identifies the characteristics of photovoltaic output and load curve in the outer layer, while in the inner layer, based on the source-load matching mechanism, it divides the transmission channel into multiple target spaces according to the characteristics of water, light and load. The model employs the coupling linkage mechanism of intra-layer target classification and inter-layer global search to solve the power allocation of the transmission channel and obtain the power distribution in each target space. The results of the case study of the hydro-photovoltaic complementary system in the Xizang section of the Lancang River show that the constructed model can effectively guide the operating conditions of the system to approach the target preference region, and the formulated scheduling scheme can meet the requirements of short-term power curtailment, fluctuation risk control and power peak regulation, verifying the rationality of the model.