Abstract: In order to improve the steering behavior of the vehicle, three control programs of ideal steering ratio of steer-by-wire system(SBW) are introduced: the first is deduced by yaw rate, the second deduced by lateral acceleration, and the third deduced by yaw rate and lateral acceleration. The three control programs are brought into vehicle model and Matlab/Simulink. Influence of variable steering ratio control on vehicle handling stability is then analyzed, and the merits and drawbacks of the three programs are compared. Simulation results showed that the third program synthesizes the former two programs, and has the best integral performance.