The study of pedestrian evacuation in channels with different structures is important among optimizing through efficiency, avoiding accidents and designing passageway. This paper establishes a macroscopic model for T-shaped channel with a number of controlled entrances basing on the law of mass conservation. Then, with the method of cascade, a kind of sliding mode controller is designed to achieve the control target of avoiding the blocking and maximizing the pedestrian flow of the whole model, the stability of the system is proved by the Lyapunov stability theory and the boundary layer method is applied to restrain the chattering of the controller. Finally, the simulation result is given to show the efficiency of the sliding mode controller and the improvement brought by the boundary layer method.