For the characteristic of the car-like mobile robot, the formation control algorithm is proposed based on the trajectory tracking. The shape of formation is determined by the parameter matrix. The virtual robot is generated according the leader robot and related formation parameters, translating the formation control problem into the trajectory tracking problem between the following robot and virtual robot. The Lyapunov function of the trajectory tracking system is constructed by using the backstepping method. The trajectory tracking controller is obtained by making this function negative. Three groups of experiments are designed in the Microsoft robotics developer studio 4. The simulation results show the effectiveness of the presented method.