Through the numerical simulation of the intake with bell tube,this article compared the difference between the fitting formula of the air flow obtained by the blowing experiment and the CFD(Computational Fluid Dynamics)method,verified the accuracy of the CFD method,and analyzed the pressure distribution of the wall of the bell tube.The research results show that the fitting formula obtained by CFD method is in good agreement with that obtained by the blowing experiment,which indicates that CFD method can assist or even replace the blowing experiment to get the air flow calculation formula;the pressure distribution of the bell tube affected by the flow field of the intake is uneven,so the impact of the intake should be considered when performing the blowing experiment;as the length of the bell tube is 1.23r(r represents the radius of the intake),the pressure probe should be located in the range of 0.68~0.98r along the direction of the air flow,that is,0.55~0.8 times the length of straight section the bell tube.