Abstract: A time domain channel estimation method in MIMO-OFDM systems by tracking the delay-subspace is proposed.The time impulse response is estimated by transmitting known pilot symbols,and the estimation performance is improved by the Givens rotation based delay-subspace tracking and amplitudes tracking based on the LMS filtering.Simulations proved that the time domain channel estimation by tracking the delay-subspace can track faster fading channels,and is more accurate and yet of low complexity.