Abstract: The optimization of ergodic channel capacity is investigated for multiple-input multiple-output（MIMO)multiple antenna systems with co-channel interference when the covariance feedback is available at the transmitter.An equivalent form of the co-interference component is first derived.Then an optimal capacity estimation algorithm is proposed by performing gradient projection algorithm which is based on nonlinear programming theory.Finally，Monte-Carlo simulation is given.The numerical results show that the performance with the proposed algorithm is close to the optimal one which is obtained by water filling algorithm when both the interference power and the correlation between antennas are strong.