Due to the multiplexing, the user has a strong co-channel interference with each other in the multi-user self-adaptive modulation system. In this case the system performance could be deteriorated by the traditional channel equalization algorithm, so an improved channel equalization algorithm is brought forward in this paper. The key point in this algorithm is to use the multi-user joint detection method to improve the veracity of the channel equalization. The simulation results show that the new algorithm has about 1dB increment.