This paper describes design of active steering system for Automated Guideway Transit (AGT) vehicles. The modeling of the AGT vehicles with active steering system is carried out first. The constructed vehicle model includes lateral transition, roll and yaw motion for vehicle body, front bogie and rear bogie, respectively. The dynamics of actuator that produce the steering torque is also considered. Optimal regulator control theory is used to design the controller for the active steering system. Curving performance of AGT vehicle with active steering system is evaluated by simulation. Simulation results show that the active steering system is effective in curving performance.