The unsteady pressure pulsation in a double channel sewage pump was numerically simulated by using combination of the developed standard k-ε turbulence model and the Mixture multiphase flow model. The simulation results were in agreement with the experimental ones, which indicated that the numerical model and the calculation methods are feasible and can be used to predict the pressure pulsation in a double channel sewage pump. The changes of pressure fluctuation under different particle diameter and particle volume fraction were analyzed by setting some monitoring points in the volute. The simulation results show that the pressure pulsation inside the pump changes obviously with the variation of particle properties, the pressure fluctuation intensity of volute circumference generally gets weaker with the addition of certain amount of particles and the maximum decreases by 34.80%. The pressure pulsation of TP1~TP3 near the tongue is sensitive to particle properties.TP1 is located at the lower end of the tongue and the angle between the volute outlet and TP1 is 15 degrees, TP2 is located at the tongue intermediate position and TP3 is located at ninth section of volute near the tongue. The dominant frequency of pressure pulsation at TP1 usually is not the blade passing frequency because of the influence from the tongue backflow, while the dominant frequency at TP2 and TP3 is the blade passing frequency. Due to tongue, the particles around TP3 accumulate easily, which results in unusual fluctuation of static pressure. Selecting the appropriate particle size or particle volume fraction can contribute to weaken the pressure fluctuation intensity in TP3.