Usually the capacity of the chilled water pump is at the highest temperature, full occupancy rate, and on this basis to leave 10%~20% allowance design, pump system long-term fixed maximum water flow, due to the season, day and night and housing rate changes, empty Figure 1 central air-conditioning working principle diagram adjustment actual thermal load in most of the time is far less than design load. Compared with the maximum design load (load rate 100%) that determines the pump flow and pressure, in a year, the load rate under 50% operating time nearly half, the general chilled water design temperature is 5~7℃, and in fact, most of the year for most of the time chilled water temperature is only 2~4℃, that is, the pump is full power operation, The energy loss of pipeline is increased, and the conveying energy of pump running is wasted. This is the ineffective use of energy, and through the frequency conversion speed regulation technology can achieve automatic regulation of flow and significant energy-saving effect.