A joint optimal dispatch model for hybrid power systems is proposed to meet the demand for secure, economical and sustainable power supply. The uncertainty of wind power, solar photovoltaic power generation and load forecasting, the security requirements of power grid and the operation characteristics of different power sources are comprehensively analyzed, and a joint optimal dispatching model considering wind power, solar photovoltaic power, cascade hydropower, thermal power, pumped storage and other hybrid power systems is established; Based on the IEEE 39-bus system, a hybrid power simulation system is constructed by combining the power composition ratio, generator distribution and basin distribution of a provincial power grid in China; The simulation results of natural scenarios under different hydraulic, wind and load conditions show that the simulation results are in line with the actual operation situation, and the proposed model provides a reference for the optimal dispatching scheme, security management and stable operation of the hybrid power system.