The invention discloses a combined type water cooling system for a motor and a frequency converter. The system comprises a circulation circuit formed after a closed pure water cooling device of the frequency converter is connected with a motor cooler in parallel and then connected with a water outlet of the motor cooler, a voltage stabilizing device, a circulating water pump, an electric three-way valve, an air cooler, a buffering water tank, an air-cooled chiller unit, a filter and a water inlet of the motor cooler in sequence through a pipeline, and an electric heater is installed on the buffering water tank or the pipeline. The system further comprises a make-up pump which is connected with the buffering water tank through the pipeline and a valve. The other end of the electric three-way valve stretches across the air cooler to be connected to the pipeline, the voltage stabilizing device, the circulating water pump, the electric three-way valve, the make-up pump, the buffering water tank, the electric heater and the filter are integrated into a module, and the air cooler and the air-cooled chiller unit are each of an independent module or are integrated into one module. The system is capable of saving water and energy, environmentally friendly, and high in integration degree.