In the OFDM/OQAM system, higher pseudo pilot power means more accurate channel estimation. According to this principle, an effective channel estimation method based on the improved preamble structure with higher pseudo pilot power was proposed. On the basis of the previous preamble structure, the preamble structure with highest power was improved and its channel estimation method was proposed. Because of the lack of enough prior knowledge of receipt signal, the channel is unable to be estimated. The pre-decision method was utilized to solve this problem. The error caused by the pre-decision was reduced through iteration, thus the estimation accuracy was improved. Simulation results prove that the proposed preamble structure shows better channel estimation performance and higher spectral efficiency.