Abstract: An adaptive transmission power allocation(ATPA) scheme is proposed for Turbo-BLAST(Turbo-Bell laboratories layered space-time) system with imperfect channel state information(CSI).Aiming at minimizing the bit error rate(BER) of the Turbo-BLAST system,the proposed ATPA scheme is suitable for different modulations like MQAM and MPSK.At the transmitter,the ATPA scheme is applied to allocating proper power to achieve the minimum BER with the constraints of the total transmission power.At the receiver,the iterative soft interference cancellation detection algorithm which takes the error of channel estimation into account is used to improve BER performance further.Simulation results show that the proposed ATPA algorithm is effective to improve BER performance of Turbo-BLAST system with imperfect channel state information.