This paper presents a flowrate equation for the multiple-jet vanewheel water meter through the analysis of the driving torque and retarding torquees on the rotor of the meter by virtue of the basic principles of fluid mechanics. Then a characteristic curve equation is further developed. The theoretical characteristic curves show areasonable agreement with theexperimental results. The characteristic curve equation has the advantage of showing the rclations between design parameters of the meter and their influences on the meter performance, and giving satisfactorv explanations of the shape of the charcteristic curve.The mathematical model presented in this paper can be used to design the vane-wheel water and provide a theoretical clue for predicting and improving the meter performance.