The common flow acquisition methods in the flow test are conventional hydrometric cableway current meter, ultrasonictime difference method, acoustic Doppler current profilers(ADCP) and radar wave current meter. According to Bernoulli's law, theincrease of flow velocity is accompanied by the decrease of fluid pressure. That is, the Venturi phenomenon that the flow velocityincreases when the confined flow passes through the reduced cross section. This phenomenon has been widely applied to measurethe flow rate of single -phase steady fluid in closed pipelines. Based on the Venturi effect and Venturi model, the equivalentformula of Venturi river is derived. In conclusion, the calculation of the method produces higher precision which can meet thestandard requirements of flow test.