A case study of typhoon cyclone was made by means of synoptic and dynamic methods.Because the practice of weather forcast shows that the vertical velocity may be used as a better indication for cyclone development,the emphasis was put on the computation analyses of the vertical velocity field in the cyclone region.By using interpolation,an attempt was made to compensate the errors in calculating divergence caused by the wind data.The computed results are in agreement with the cyclone observations and the satellite photographs.