Abstract: Channel estimation and tracking algorithms in frequency domain of MIMO-OFDM(multiple-input multiple-output and orthogonal frequency division multiplexing) system are investigated.The existing channel estimation algorithms in frequency domain are analyzed and compared,then an improved channel estimation and tracking scheme is proposed.In the scheme,the initial channel estimation information is attained with the help of an estimation method based on orthogonal training symbols,and the time-varying channel parameters are tracked with an iterative joint channel estimation and signal detection algorithm.Three channel estimation and tracking schemes in frequency domain are simulated in the typical indoor environment,and the result shows that the proposed scheme can bring obvious performance gain with small number of iterations.