This study investigated the mechanical, thermal, and morphological properties of glass fiber-reinforced polypropylene (GFPP) composite plates before and after ultraviolet (UV) aging, to evaluate the effects of UV-resistant additives and protective films on enhancing UV durability. The findings provide technical support for the application of composite materials in lightweight freight vehicle bodies. The results demonstrated that the tensile strength of unmodified samples decreased by 19% after 2 000 hours of UV exposure. In contrast, samples treated with anti-UV additives and coated with UV-resistant films exhibited only a 4% reduction in mechanical performance. Fourier transform infrared spectroscopy (FTIR) was employed to quantitatively analyze the evolution of carbonyl groups (C＝O), revealing that synergistic UV protection effectively suppressed molecular chain scission. Specifically, unprotected samples showed a significant increase in the carbonyl absorption peak at 1 740 cm^-1 (a characteristic marker of polypropylene degradation), while protected samples exhibited minimal changes. Scanning electron microscopy (SEM) further confirmed severe surface pulverization and cracking in unprotected samples, whereas protected samples maintained structural integrity.