Abstract: In order to analyze the characteristics and the major influence factors of the pressure fluctuation in the double-blade pump, the RNG κ-ε turbulence model was applied and the fluid field in the impeller, volute casing and the inlet extended section of the impeller under three operating conditions was computed. Based on the analysis of simulation data, the time-domain spectrums and frequency spectrums of pressure fluctuation were obtained. It showed that: the pressure wave was a periodic sine one in the double-blade pump and the period at inlet was double than other parts. The pressure fluctuation was effected by the rotor-stator coupling. The dominant frequency of the inlet pressure fluctuation of impeller was approximately equal to the impeller passing frequency, and that in the impeller-volute casing coupling part, and the outlet of volute casing was equal to the product of impeller rotational frequency and number of blade. The dominant frequency at the same monitoring point was constant but with different amplitude in different flow rate, high amplitude in low flow rate and minimum in design rate. In the impeller-volute casing coupling, the pressure fluctuation will start to decline along the direction of impeller rotation from the tongue. The conclusion will provide an essential guide to master the principles and characters of the pressure fluctuation in the double-blade pump.