The domestic high-power RF slab CO2 laser has no dielectric film on the surface of the copper electrode. The surface of the bare copper is easily oxidized during the discharge process. It is damaged by laser electronic sputtering. The waveguide loss is seriously, which affects the light output efficiency of the laser. In order to solve the above problems, the Al＋Al2O3 hybrid waveguide dielectric film was developed. The composition of electrode film was analyzed and the anti-electron sputtering ability was tested. Experiments was conducted to detect the anomalous dispersion of CO2optical waves on the film surface. The micro analysis shows the film is composite of Al and O, the atomic ratio is over 2∶3, and the micro-structure is Al＋Al2O3, which meets the design of electrode surface film structure; the reflectance under different incident angle was tested, when incident angle is between 10°to 170°, the highest reflectance of Al2O3 film surface to CO2 with a wavelength of 10.6 μm is 85%. Discharge test shows the average optical efficiency of coated electrode laser is 10.4%. However, that of naked Cu electrode laser is 6.5%.