The invention relates to a control system for reducing temperature and saving energy of operating water of a vacuum pump, comprising a refrigeration cycle system, an external cycle system, an electric control, a rack and a cover; the control system is characterized in that a set of refrigeration cycle system is provided, the control system is also provided with an internal cycle system and an operating water system; the internal cycle system is composed of an evaporator, an internal cycle pump, an expansible water tank, an exhaust valve, a water heat exchanger and a water pipe; the operating water system is composed of a water heat exchanger, another exhaust valve, an operating water inlet pipe and a water outlet pipe, the operating water system is connected with the vacuum pump; and the internal cycle system exchanges heat with the refrigeration cycle system through the evaporator and exchanges heat with the operating water system through the water heat exchanger; the external cycle system exchanges heat with the refrigeration cycle system through a condenser, the condenser is fixed on the rack, the external cycle system is fixed on the rack through an external cycle pump, the electric control is connected to the refrigeration cycle system through a first branch line and a compressor, the electric control is connected to the internal cycle system through a second branch line and the internal cycle pump, the electric control is connected to the external cycle system through a third branch line and the external cycle pump; the cover is connected to the cover through bolts; the rack is connected to the internal cycle system through the internal cycle pump, the water heat exchanger and the evaporator; the rack is connected to the operating water system through the water heat exchanger.