Abstract : In this research, the performance and efficiency of a centrifugal pump under operation are diagnosed with high precision by measurement of electric current, voltage, flow rate, and pressure. Moreover, mechanical faults (misalignment etc.) and the faults in fluid (cavitation etc.) were diagnosed precisely with the vibration signals, and the reason of efficiency fall was clarified theoretically and experimentally. In this report, we proposed the condition diagnosis method for pump equipment by using statistic filer, dimensional symptom parameter in time and frequency domain and Weibull probability distribution, and the changing trend of pump efficiency in fault state was clarified experimentally. We also show the practical surveillance example of condition and efficiency for a centrifugal pump.