This paper examines the feasibility and the efficiency of a multiple-relaxation-time lattice Boltzmann model(MRT-LBM) for simulating open channel flows in engineering practice. A MRT-LBM scheme for 2-D shallow water flows taking into account of the bed slope and the friction is proposed. The scheme’s reliability is verified by benchmark problems and the simulation capability is improved by implementing the scheme on a graphic processing unit(GPU). We use the method to analyze the flow characteristics in the connecting open channel of two cascaded hydropower stations. The flow fields and parameters such as the water depth, the flow rate, and the side-weir discharge, under different operating conditions, are analyzed. The factors affecting the accuracy and the efficiency are discussed. The results are found to be reasonable and may be used as a guidance in the project design. It is shown that the GPU-implemented MRT-LBM on a fine mesh can efficiently simulate two-dimensional shallow water flows in engineering practice. This paper examines the feasibility and the efficiency of a multiple-relaxation-time lattice Boltzmann model (MRT-LBM) for simulating open channel flows in engineering practice. A MRT-LBM scheme for 2-D shallow water flows taking into account of the bed The scheme’s reliability is verified by benchmark problems and the simulation capability is improved by implementing the scheme on a graphic processing unit (GPU). We use the method to analyze the flow characteristics in the connecting open channel of two The flow fields and parameters such as the water depth, the flow rate, and the side-weir discharge, under different operating conditions, are are. The factors affect the accuracy and the efficiency are discussed. The results are found to be reasonable and may be used as a guidance in the project design. It is shown that the GPU-implemented MRT-LBM on a fine mesh can efficiently simulate two-dimensional shallow wate r flows in engineering practice.