Abstract: As a pre-processing technique, the Wiener filter can be used to suppress stronginterference and noise. The general solution of optimum transfer function has been found for the multi-channel system. By using an inverse matrix formular, a simple expression of optimum transfer function can be derived in the case that only one interference is present. The formula for calculating the system gain is presented. The asymptotic performance of system gain as input interference to signal ratio increasing to infinite is evaluated. When the interference is distorted not only in phase but also in amplitude as well, the system gain can be evaluated in some particular cases. The results of numerical calculation are given in this paper.