In order to solve the problem of the change in lift and drag characteristics caused by the change in the compression of the nose gear during the take-off and roll-off of the UAV, comprehensive consideration of factors such as engine speed, propeller efficiency and ground friction was established to establish the UAV ground roll model. The influence of the change of the nose gear stiffness on the take-off and running performance of the UAV was studied, and a simulation model of the whole aircraft was established by Simulink. The results show that when the take-off weight is constant, the lift coefficient of the whole aircraft changes linearly with the change of the front landing gear compression. With the increase of the front landing gear stiffness, the UAV's three-wheel sliding distance, front wheel off-ground angle of attack and front wheel The ground clearance speed is reduced to a certain extent. The simulation results are consistent with the theoretical analysis, which verifies the validity of the model.