Channel state information(CSI)is essential for downlink transmission in millimeter wave(mmWave)multiple input multiple output(MIMO)systems.Multi-panel antenna array is exploited in mmWave MIMO system due to its superior performance.Two channel estimation algorithms are proposed in this paper,named as generalized joint orthogonal matching pursuit(G-JOMP)and optimized joint orthogonal matching pursuit(O-JOMP)for multi-panel mmWave MIMO system based on the compressed sensing(CS)theory.G-JOMP exploits common sparsity structure among channel response between antenna panels of base station(BS)and users to reduce the computational complexity in channel estimation.O-JOMP algorithm is then developed to further improve the accuracy of channel estimation by optimal panel selection based on the power of the received signal.Simulation results show that the performance of the proposed algorithms is better than that of the conventional orthogonal matching pursuit(OMP)based algorithm in multi-panel mmWave MIMO system.