The steering-by-wire system is different from the traditional steering system.It is a complicated system composed of steering motor,steering mechanism,steering angle sensor,steering torque sensor and ECU.System performance was influenced by parameter uncertainties,unmodeled dynamics and the front tire selfaligning moment.According to the design demand of the steeringbywire system robust,a new PIλDμ control strategy based on fractional calculus was proposed,which can ensure the robust of the steering-by-wire system during the special range of frequency.The five design parameters of controller were achieved by the method of optimum.Oustaloup method was used to simulate the fractional controller,and the simulation results showed the effectiveness of the control method to improve the robust of the steering-by-wire system.