The invention discloses a channel estimation method for an OFDM system based on compressed sensing. The method disclosed by the invention has the advantages that under the condition that the sparseness is unknown, a bit error rate can approach a bit error rate achieved by the OMP algorithm, and mean square errors are slightly higher than mean square errors achieved by the OMP algorithm; the bit error rate and the mean square errors are much lower than a bit error rate and mean square errors achieved by the SAMP algorithm; and therefore, the channel estimation performance under the condition that the channel sparseness is unknown can be greatly improved.