Abstract: By using the barotropical vorticity equation with thermal forcing and dissipation terms,sixteen numerical experiments whose integration times are longer than seven model days are performed in order to investigate tropical cyclone motion under the influence of enviromental,flow and local thermal forcing.Resuits show that in various range of the parameters describing the intensity of environmental flow,the thermal forcing and tropical cyclone size,various tracks can be reproduced,which include counterclockwise revolution,looping motion,northwestward shift and abrupt turning northward,exhibiting features of nonlinear systems.