Based on the theoretical model analysis of differential pressure flowmeter under pulsating flow condition, the algorithm of eliminating the influence of flow derivative term based on the double-channel differential pressure is given. The flow field in Venturi tube is simulated by FLUENT software, and then the calculation method of pulsating flow is verified. The simulation results show that the maximum error can be up to 100% when calculating the fluctuating flow using single-channel pressure, and the maximum error can be reduced to about 5% when calculating the fluctuating flow using double-channel differential pressure. The results show that the calculation method of double-channel differential pressure method can effectively improve the accuracy of pulsating flow measurement, and has the value of further popularization and application.