In order to obtain the pressure pulsation characteristics of the model of one axial flow pump unit named Paihekou station under different cavitation conditions, the monitoring points of pressure were set near the impeller inlet, the impeller outlet and the vane outlet, the test was conducted by applying a dynamic pressure sensor system under four different head conditions with three different cavitation conditions of no cavitation, critical cavitation (pump efficiency decreased by 1%), deep cavitation (pump efficiency decreased by 3%). The test results showed that the pressure pulsation curve at the inlet of the wheel was a smooth and approximate sine curve, and the amplitude of the pressure fluctuation curve at the outlet of the impeller was the largest and showed obvious second harmonic characteristics in a rotating cycle under the high head condition without cavitation. The time domain characteristics of pressure pulsation of vane outlet were similar to that of impeller inlet. The results of FFT showed that the main frequency of each monitoring point under different working conditions was the integral frequency doubling of the blade passing frequency. With the deepening of cavitation, harmonic frequency near the main frequency of each monitoring point was gradually moved to the low frequency section. The vane outlet and impeller inlet were less affected by the blade passing frequency and showed similar frequency characteristics.