To avoid the chattering disadvantage of sliding-mode control (SMC), in this paper, a quasi-sliding mode controller is proposed for real-time fine control of a nonholonomic mobile robot. First, the dynamics of mobile robot is analyzed by Lagrangian formula. Then, the quasi-sliding mode controller is used to generate the control torque that drives the mobile robot, such that the linear and angular velocities of the mobile robot follow the desired velocities. At last, computer simulation results confirm the effectives of SMC.