Abstract: The multi-channel signal subspace algorithm for speech enhancement is studied, and the algorithm's parameters which affects the performance are analyzed.A simple and an effective method for estimating the noise variance are given. Through analysis, it is proved that the multi-channel signal subspace algorithm can denoise obviously and make very little voice injury. Compared with the single-channel subspace speech enhancement algorithm,the multi-channel signal subspace algorithm can not only upgrade the performance, but also have no increase in the amount of calculation. The muti-channel signal subspace algorithm has been used in speaker recognition system, and compared with other speech enhancement algorithms, such as Delay and Sum Beamfonning, Beamforming and Wiener Filter, and Linear Constraint Minimum Variance Beamfonning.The experimental results show that the muti-chanel signal subspace algorithra can effectively improve the recognition rate of the speaker recognition system in noisy environment.