Abstract: Eigen-beamforming technique is introduced in two typical multi-antenna systems space-time block coding and vertical bell-labs layered space time.When the channel covariance information is known by the transmitter,optimal power allocation algorithm for eigen-beamforming is proposed based on minimizing the transmission errors.Also,it is indicated that the algorithm can be simplified when the channel is independent-identically distributed channel.By simulation and analysis,eigen-beamforming can greatly improve the performance of multi-antenna system when this power allocation algorithm is adopted and the performance improvement still exists when there is correlation between transmit antennas.