Accelerated weathering tests were performed to inspect the effect of Good Rite antioxidant on low-density polyethylene (LDPE) films. The LDPE pellets and antioxidant particles were blended in a twin-screw extruder then were blown to films by film blowing machine. Thermal decomposition, mechanical properties and chemical changes have been investigated through the DSC, TGA tensile test and (FT-IR). As observed, the weathering changed the thermal behavior, particularly a degree of crystallinity. As depicted in TGA the increasing of temperature at 50% of its initial weight (T50%) indicated that LDPE films were more stable after weathering. Weathering effect on mechanical properties of different samples is obvious by the reduction of tensile strength as the increase of weathering period. Additionally, carbonyl Index calculated from IR absorption spectra proved the effectiveness of antioxidants.