Abstract: With the increasing demand of flexible electronic products for efficient thermal management, the preparation of flexible thin films with high conductivity has attracted more and more attention in recent years. Cu and Cu-Ag thin films are prepared by laser direct writing technique on polyimide (PI) substrate. The phase analysis and structure characterization of the two films show that the copper nanoparticles and silver nanowires are sintered by partial melting of their surface under laser irradiation. By comparing the resistance changes of prepared copper and Cu-Ag thin films at different temperatures for 7 days, it is concluded that the introduced silver improves the overall oxidation resistance of the composites. The thermal diffusivity and thermal conductivity of the two composites are tested, and it is found that the thermal conductivity of Cu-Ag/PI is significantly improved, showing better thermal performance than Cu/PI. This work provides a quick, simple and economical method for the preparation of Cu/PI and Cu-Ag/PI composites with good thermal stability.