In this paper, we investigate adaptive resource allocation strategy for downlink multi-input-multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) system. We design a transmit scheme as a concatenation of dynamic sub-carriers and bit assignment, adaptive modulation and beam-forming. Our adaptive goal is margin adaptive optimization, which minimize the total transmission power subject to a target BER performance constraint on each sub-carrier, while meeting a constant bit rate. By use of Rayleigh fading model assumption, we introduce a new concept: the channel feedback coefficient, so as to compensate the error inducted by feedback channel. Simulation results show that the proposed resource allocation scheme outperforms the multi-user MIMO-OFDM with static allocation technique, and can lessen the performance loss caused by channel state information feedback error.