The flow pressure pulsation is large axial flow pump running stability of the key factors of the time correlation analysis of transient flow theory and large eddy simulation method of axial flow pump of unsteady flow were obtained under different conditions of water pump pressure pulsation and the measured results by head and power comparison show that the proposed method can be more accurate the pump flow characteristics of axial flow pump maximum pressure pulsation occurs in the impeller inlet pressure pulsation frequency is mainly affected by the rotational frequency of the impeller in the control at the inlet and outlet of impeller from hub to tip pressure increasing and in the middle of guide vane and guide vane outlet of the opposite result is far from optimum operation point fluctuation the relative amplitude is greater in the flow conditions of pump pressure pulsation is about 2 times of the optimal condition.