Based on the correlation property of sequences，a time-domain channel estimation algorithm for Multi-Input Multi-Output Orthogonal Frequency Division Multiplexing(MIMO-OFDM) is proposed. The real training sequences with perfect correlation property is inserted between OFDM symbols, then the channel impulse response in time domain can be obtained by calculating the cross-correlation between the received sequences and trained sequences. The estimation performance is further improved by the estimation of channel order. The results of both theoretical analysis and experiment show that the proposed method has more excellent estimation performance with higher system transfer efficiency than the existing methods.