In this paper,the selfrecording data over denser surface are used to analyse strong surface wind and its fluctuation in the process of typhoon-caused severe rain corresponding with the genesis and movement of the rain clusters in downstream as well as oscillation of rain intensity.The values of nonlinear terms in the divergence and vorticity equation are computed.Local variation of the divergence caused by the inhomogene-ous distribution of the surface wind velocity and the effects of interaction between vorticity field and divergence field on trigger process of mesoscale system of severe rain are discussed.Finally, it is also pointed out that it is helpful to be knowledyed of the feature and variation of surface wind field in order to catch of mesoscale system of severe rain and to make the short-time forecast of it.