This paper proposes a general multichannel system reproduction method. Firstly, relative to original multichannel system, a general global model is build up by guaranteeing sound pressure and the direction of particle velocity at the receiving point constant, and making the square error of particle velocity magnitude at the receiving point as little as possible. Then the model is equivalent to a least squares problems with non-negative constraints, it can be worked out by existing mature algorithms, and the global optimal solution of simplifying multichannel system are obtained. The proposed method can be used to simplify 22.2 multichannel system to 10.2 and 8.2 multichannel system, objective and subjective experimental results demonstrate that it performs better than traditional method.