The methods of distinguishing radar targets and active decoy are studied based on the radar system taking two receiving stations as a background. Firstly, the doublestation polarization scattering matrix and the doublestation diagonal polarization ratio are defined, and the polarization scattering properties of radar targets and active decoy are studied. Then, a discrimination method is proposed to discriminate the polarizationchanged deceptive jamming by using the discriminate parameter of doublestation diagonal polarization ratio, and the discrimination algorithm is also designed. The simulation result shows that by using the identification algorithm, the correct identification probability of active decoy is always 100%, and the correct identification probability of a radar target can also be over 90%. The effectiveness and the feasibility of the algorithm are validated.