Provided are an energy-saving control method and system for a river water source heat pump system. The method comprises the following steps that S1, building standard cold and heat energy consumptionlarge data are built; S2, according to the building function, energy using time and load distribution difference, by combination with the building standard cold and heat energy consumption large data,building refinement partitioning is conducted, a cold and heat energy requirement dynamic curve of all subzones of a building is generated, and the dynamic curve is updated once at fixed intervals; and S3, according to the cold and heat energy requirement dynamic curve of the building, the large hysteresis quality and nonlinearity of an air conditioner system are considered, the river water source heat pump system is divided into an equipment starting stage, a steady-state operation stage and an equipment halt stage, and staged control is conducted; and the temperature changes of river waterare monitored in real time, and when the temperature difference of inlet and outlet water of a river water source heat pump unit exceeds the set value, corresponding water pumps are controlled in a variable-frequency mode, and the water flow is adjusted. The invention further discloses the energy-saving control system for the river water source heat pump system. The energy-saving control method and system for the river water source heat pump system have the advantages of being high in efficiency, stable, free of pollution, small in energy consumption, remarkable in energy-saving effect and thelike.