Abstract: An iterative detection of OFDM signals for sparse channel is proposed in this paper.Pilot based channel estimation is used as the initialization of the detection.Expectation Maximization algorithm is then used to detect OFDM signals iteratively.The path delay information，noise power and the covariance matrix of the channel response are needed in this method，so the methods of estimating all these channel parameters are also given.The simulation results prove the efficiency of the iterative algorithm，and also prove that by using the estimation parameters of the channel，the performance can nearly approximate the perfect channel state information.