A novel class of periodically changing features hidden in radar pulse sequence environment, named G features, is pro-posed. Combining fractal theory and Hilbert-Huang transform, the features are extracted using changing characteristics of pulse parameters in radar emitter signals. The features can be applied in modern complex electronic warfare environment to address the issue of signal sorting when radar emitter pulse signal parameters severely or even completely ovedap. Experiment results show that the proposed feature class and feature extraction method can discriminate periodically changing pulse sequence signal sorting features from radar pulse signal flow with complex variant features, therefore provide a new methodology for signal sorting.