1, single-stage pump is only one impeller pump, the highest lift is only 125 meters; 2, multi-stage pump refers to the pump with two or more impellers, the maximum lift can be more than 125 meters; multi-stage pump in the single Pump head needs to be equipped with two-stage motor, the impeller can be increased by increasing the number of four motor, which can improve pump life and reduce unit noise, but the multi-stage pump repair relative single-stage pump is difficult a little. 3, the pump actually needs less than 125 meters head, according to pump room area, pump price (multi-stage pump generally higher than the single-stage pump price), and other factors considering the choice of single-stage pump or multi-stage pump. As technology advances, single-stage impeller pump can improve the pump lift by increasing the pump speed, instead of multi-stage pump, but the price is a little expensive.