Blends PP/PA (100:18) was prepared by means of melt-mixing using a twin- screw extruder, and the effects of γ-radiation in air on their stability under lower radiation dose (≤5kGy) at a fixed dose rate of 110Gy/min have been researched. The effects of nylon-6 (PA-6), trimethyrol-propane trimethacrylate (TMPTA), maleated polypropylene (mPP) and γ-radiation dose (D) on melt flow ability, mechanical property, thermal property and morphology of the blends were investigated. It was noted that its tensile strength (σs) and Young’s modulus (E) increased with the addition of TMPTA, while its elongation (ε) and melt flowing rate (MFR) decreased. Compatibilizer mPP and TMPTA could improve the compatibility of the PP/PA-6. Its heat resistance was superior to PP. There was little effect of γ-radiation in air on their σs, E and ε when irradiation dose ranged from 0.1 to 5.0kGy.