In this paper, the effects of JTIDS and TACAN systems working at same site on the performance of TACAN system were investigated. Deep analysis from several aspects including their work system, mode, and signal waveform and signal structure was made. The results showed that even if the two systems in the co-site working, TACAN performance indicators are only slightly reduced. The results provide theoretical basis for electromagnetic compatibility similar to that of JTIDS and TACAN.