According to the different flight principle and movement characteristics of takeoff at two points and takeoff at three points, two models of mathematical simulation under condition of different takeoff modes are established respectively in this paper. Based on the aerodynamic characteristics of aircraft and the characteristics of landing gear system, the simulation results are carried out according to the whole design parameters, and the performance data of different takeoff modes are given. Taking a certain type of aircraft as an example, the takeoff performance program is programmed to calculate the takeoff performance. Finally, the effects of two different takeoff modes on the distance and velocity of each takeoff phase are analyzed, and the relevant conclusions are given based on the actual flight characteristics of the aircraft，and the accuracy of the simulation model is verified, and a fairly good takeoff mode is given to guide a pilot in flight.