This paper focuses on the countermeasures of airborne towed radar active decoy. Moreover, a detection and suppression scheme of Towed Radar Active Decoy (TRAD) using polarization information is proposed. A full-polarization radar echo model with the presence of jamming is established. Furthermore, based on a monopulse radar angle measurement system, the difference between the characteristics of TRAD and radar targets in different polarization channels is analyzed. A detection scheme is proposed using the differences of target Polarization Scattering Matrix (PSM) divergence with the presence and absence of TRAD. Subsequently, the corresponding jamming suppression algorithm is developed. The efficiency and advantages of the proposed algorithm are validated via theoretical analyses and simulation studies. This paper provides an effective method to detect TRAD and can provide a significant reference for improving the precision strike of terminal guidance radar under jamming.