The invention discloses a variable frequency control system of a water-cooled semiconductor refrigeration fruit/vegetable freshness preservation tank. The variable frequency control system uses an ARM as a control chip, comprises a temperature sensor transfer circuit, a relative humidity sensor driving circuit, a semiconductor refrigeration chip control circuit, a radiating fan control circuit, a refrigeration fan control circuit, a water pump control circuit, a display screen driving circuit, a prompt circuit, a key control circuit and a power supply conversion circuit, and realizes the control system touch screen control, the temperature control object selection, the refrigeration chip PID control, the water pump PID control, the radiating fan classification control, the cold-end fan classification control, the in-tank temperature field detecting control, the in-tank humidity detecting function and the alarming function setting. The variable frequency control system overcomes such defects as extensive control, high energy consumption, high temperature overshoot and large temperature difference in a traditional semiconductor refrigeration freshness preservation tank control system.