Aimed at the problems that the width of taxiway, the separation between taxiways and other fixed objects of the flying area fails to meet the standard requirement and the risk of aircraft operation, this paper analyzes the route deviation caused by aircraft during taxing. Based on the extreme value theory, by using the main principle of generalized Pareto distribution, the high tail of the data is analyzed, the appropriate threshold is selected and the exceed threshold model is established. On this basis, the selection of the data base sample is analyzed. Then, the paper determines the appropriate threshold and tunes the model parameters, and finally the taxiway deviation probability distribution is given. By running the taxiway deviation risk model.