In order to study the influence of the position of the pressure intake on the measurement of periodic fluctuating flow through Venturi tube, the flow field of sinusoidal fluctuating flow in the lower venturi tube is simulated by FLUENT software. The differential pressure between the flow rate and four groups of pressure intake in a single cycle under different fluctuating frequencies and amplitudes is obtained. The four groups of differential pressure are used to calculate the fluctuating flow rate separately, which is a mistake in the calculation of flow rate. The differences were compared and analyzed. The results show that the different axis positions of Venturi tube pressure intake will lead to different integral values of reciprocal cross-sectional area between pressure intake, which will affect the measurement error of pulsating flow.