Abstract: In this paper,the equations of motion of vortices in baroclinic atmosphere are derived in the light of classical hydzodynanucs.Six factors determining the motion of vortices are discussed.Physical interpretation and some coazments are given to the well-known steering principle.Application of these equations in the forecasting of the motion of typhoons are illustrated by three examples,and the results are better or as well as those of the synoptic forecasts.Possibility and limitation of their application to the motion of middle-latitude vortices are also discussed.In the appendix,there are critical discussions of the role of the internal forces and the calculation of the amplitude and period of the meandering motion of typhoons in straight steering current.