Abstract: This paper concerns trajectory tracking control of mobile robots. In order to overcome the local stability resulted from linearization design methods, a global asymptotically stable (GAS) controller is designed using backstepping method. This method breaks down nonlinear systems into low dimensional systems and simplifies the controller design using virtual control inputs and partial Lyapunov functions. The stability of the system is easily proven via the Lyapunov function. Abundant simulation results validate the theoretical analysis.