Abstract: Four stages are selected from the movement of the typhoon Yancy and four numerical experiments whose integration times correspond to the four stages by using a quasigeostrophic barotropical model. The gridpoint data of the initial fields are obtained from the intensive observations in the SPECTRUM and TCM-90 Field Experiment. Some main characteristics of the unusual motions of typhoon Yancy such as the unexpected turns in its tracks can be well simulated. The oscillation of asymmetric structure of the typhoon whose period is about 42 model hours can be also exhibited obvioursly. which may be responsible to the turns.