The channel estimation based on pilot was studied in this paper. Multi-path and timevarying statistic properties of general wireless channel were summarized. The properties of channel were analyzed, giving simulation of the SUI-3 channel models. Based on this analysis, the principles and performances of the existing channel estimation methods in block-type pilot arrangements were investigated. Based on Alamouti′s space-time coder design, a wireless OFDM system with only one receiver antenna to wireless OFDM system with two transmitters was established. An algorithm to implement channel estimation, DFT-based channel estimator at virtual carriers system, was proposed. The channel status information was reconstructed by the new algorithm according to a DFT iterative algorithm. Then the channel noise was suppressed by time domain filter methods. The results of simulation show that the method can estimate channel well. The method is proved to be effective and feasible.