The determining of cavitation monitoring threshold is the key segment of distinguishing pump running state. A series of tests have been put into effect in a laboratory to simulate the cavitation, the signal of inlet sound pressure and enclosure vibration were acquired at 1440 r/min, flow rate at 90, 100, 110, 120 m3/h. The method to determine the cavitation monitoring threshold which based on statistic theory was posed by making use of reference frequency band energy. The results of cavitation experimental study showed that the inlet pressure sound and enclosure vibration signal of pump were followed uniformity by sound pressure rule at the reference frequency band, the energy value first rose then dropped along with cavity number diminishing; using 3σ principle, the energy curve peak lower limit value was firstly acquired by the experiment, then the value of decreasing 3~5 dB was taken as the reference of cavitation threshold; the reference frequency band energy peak value of sound pressure first rose then dropped along with the increase of flow rate, and its cavitation sensitivity is stronger than the vibration signal.
