Abstract: The characteristics of bit error rate (BER) of a multi-antenna system are analysed. Because the earlier works put stress on designing the schemes to extract either maximal diversity gain or maximal spatial multiplexing gain, but failed to take full advantage of the performance of the system, a multiple-input multiple-output (MIMO) diversity-multiplexing tradeoff algorithm is proposed on the basis of adaptive allocation of code bit and power and, further, an algorithm with less computational complexity is given. Based on the BER criterion, the proposed algorithm is chosen in an appropriate mode according to the instantaneous channel state information (CSI) and makes full use of the two gains as above to serve well the anti-interference function with less computational complexity provided to adapt to practical applications. Simulation results indicated that the performance of the proposed algorithm is superior to the conventional one with high effectiveness and feasibility.