Considering that how to efficiently implement channelization and improve detection method's performance, a modified structure of dynamic channelization and a corresponding channel detection method are proposed. The input signal is decomposed into two channel signals whose spectra are complementary without aliasing by interpolating halfband filter, and then the two channel signals are filtered respectively with the analysis filter bank to realize channelization. The first detection's threshold is dynamically adjusted according to the channel environment, and the second detection uses the longer detection length. Simulation results verify the validity of the modified structure of dynamic channelization, and show that under the condition of ensuring real-time the performance of new algorithm is better than energy detection.