Nonlinear stability analysis of phase plane is one of the most classic and effective methods. Based on established two degrees of freedom (2 DOF) vehicle model, combined with magic formula tire mode, phase plane analysis is used to study vehicle motion characteristics in various initial conditions. In addition, equilibrium point and phase plane trajectories changes are analyzed under the condition of traveling in a straight line, circular motion and sine wave input. The results denote that vehicle steady state can be well determined according to analysis changes of phase plane trajectory and state variables. Namely, phase plane analysis can be well used to analyze and evaluate the trend of variables and vehicle motion characteristics.