The invention relates to a water pump efficiency, flow and lift detection method and system. The method comprises the steps of obtaining the output power f and the output frequency P,

, of a frequency changer, wherein the frequency changer is in signal connection with a water pump; and according to the output power f and the output frequency P,

, of the frequency changer, calculating the flow Qf, the lift Hf and the efficiency Eta f of the water pump. According to the water pump efficiency, flow and lift detection method and system, a controller reads the output power and the output frequency of the frequency changer; and according to the output power and the output frequency of the frequency changer, the flow, lift and efficiency of the water pump can be calculated. The structure is simple, and measurement can be achieved without installing of a pressure sensor and a flow meter; meanwhile, through PID real-time control and measurement display, the precision of measured water pump performance data is high, errors brought by manual measurement and treatment are overcome, the measurement efficiency is improved, high precision and high automation of the water pump performance measurement are achieved, the water pump performance measurement cost is reduced, and the measurement time is shortened.