Tire model for vehicle braking performance simulation analysis has been built in this paper. Through theoritical analysis, the expression of longitudinal force, side-force and self-aligning torque of the tire in joint working conditions was obtained. By means of neural network module in MATLAB, BP neural network model of the tire in joint working conditions was built. Vertical load, slipping ratio, side slip angle and ground friction coefficient were the input; longitudinal force, side force and self-aligning torque of the tire were the output, and the training sample was calculated. Finally, carrying on simulation analysis of the tire in any working conditions, related tire performance was obtained, it lay the foundation for simulation analysis of automobile dynamics.