A tractor-trailer wheeled robot (TTWR) is a kind of modular robotic system that consist of the tractor and the trailer are mechanically coupled to each other. It is impossible to obtain an exact dynamics model due to unknown parameters, or unpredictable and irregular features, external disturbance. Because of the non-holonomic constraints property, this paper proposes an adaptive robust cascade controller to guide TTWR to follow the desired trajectory. The influence from external disturbances, parametric uncertainties in TTWR are compensated by the robust-adaptive nonlinear control law at inner loop. The asymptotic stability of the whole system is point out based on Lyapunov theory. The simulation results demonstrate the good performance of the proposed controller for trajectory tracking.