The optimization ability of LCC (Liquid crystal coated C-plate, LCC) to the RQWP (Reverse wavelength dispersion quarter wave plate, RQWP) compensation characteristics under the oblique incidence is investigated based on the combination of theoretical research and experimental research. The ellipticity of the outgoing light passing through RQWP and RQWP+LCC at any angle and the influence of LCC with different RTH on the ellipticity of the outgoing light are calculated based on extended Jones matrix method. The reflectance of ambient light and color deviation at large viewing-angle of the circular polarizer made by above structures are tested respectively under the case of OLED (Organic light emitting-diode display). It is shown that the LCC can make an increase of more than 10% for the ellipticity at 45° incidence. According to the numerical simulation with different NZ value of RQWP+LCC, NZ=0.5 is proved to be the best ellipticity configuration at any incident angle under R (red light), G (green light) and B (blue light) wavelengths. The structure with RQWP+LCC could reduce the ambient light reflectance by 3% under the oblique incidence at 45° polar angle on OLED. It is difficult to produce the compensation film with NZ=0.5 directly in industrial production, while relevant conclusions in this manuscript have potential to guide similar applications.