Abstract: A new approach which using mismatched-sequence to channel estimation in OFDM systems is proposed. In the scheme, mismatchedsequence is added to OFDM signal as a training sequence at sender, the receiver calculates the cross-correlation between the received mismatched sequence with CP removed and the circular shifted mismatched filter coefficient. By making use of the auto-correlation property of the mismatched-sequence the channel impulse response can be estimated and then the channel frequency response can be acquired. Theoretical analysis and simulation results show that the new algorithm has good property of low-complexity, accurate estimation and better BER performance