In this letter, with the synthesis of usual cross-correlation detecting method and chaotic detecting method, a new detecting system for the weak periodic pulse signal is constituted, in which the two methods can play respective preponderance. Theoretical analyses and simulation studies have shown that the detecting system is very sensitive to the periodic pulse signal under strong noise background and has exceedingly powerful capability of suppressing complex noise. In this letter, with the synthesis of usual cross-correlation detecting method and chaotic detecting method, a new detecting system for the weak periodic pulse signal is composed, in which the two methods can play allow preponderance. Theoretical analyzes and simulation studies have shown that the detecting system is very sensitive to the periodic pulse signal under strong noise background and has exceedingly powerful capability of suppressing complex noise.