Doppler radial velocity photograph of mesocyclone is simulated with the Rankine Model and a method to determine mesocyclone center position and radius of maximum wind is proposed.In this method,the product of Doppler radar radial velocity(r) and distance(D) between observed point and radar position is taken as a parameter.It can be proved that the mesocyclone center is the middle point of the line from the maximum to the minimum of the parameter(r·D) and the radius of maximum wind is equal to half the distance between the maximum and the minimum(r·D) according to the geometrical relationship of radial velocity and real air flow.The result from model experiment shows that the method is much better than Wood and Browns(1992) method for estimating typhoon center and radius of maximum wind.