With regard to the principle that the pilot frequencies transmitted by different transmitting antennas must be orthogonal after being shifted,the time domain channel estimation solution based on the MIMO-OFDM channel estimation model is deduced through Least Square (LS) method.Considering that the time-domain solution involves the inverse operation of matrix,and needs massive amount of calculation,we adopt a three-dimensional pilot frequency based on space domain,time domain and frequency domain,which can reduce the complexity of channel estimation and make the channel estimation error minimum.Simulation result showed that:Compared with the traditional LS algorithm and the document algorithm,the proposed channel estimation method based on space/time/frequency domain pilot frequency has better MSE and BER performances.