In light of the issues related to the omission of crucial features and the incorrect selection of redundant features in existing feature selection methods for zero-crossing (ZC) features, this paper presents a feature selection method based on Dynamic Weights Condition Mutual Information (DWCMI). In this method, the main factor of the objective function for feature evaluation is conditional mutual information, while also incorporating a complementary evaluation criterion based on conditional mutual information to address the issue of misselecting redundant features. By introducing a dynamic weight coefficient, we can accurately measure the importance of selected features by assessing their dynamic change in mutual information, thereby avoiding any oversight of crucial features. In the process of designing the algorithm, computational efficiency is improved by buffering and reusing previously calculated mutual information. This approach avoids the issue of repeatedly calculating the mutual information. The necessity, effectiveness, and high efficiency of the DWCMI method have been verified through simulation and experimentation.