The responsiveness of typical silicon-based CMOS image sensors in the UV band is not high due to the limited penetration depth of UV light in silicon and the absorption of UV light by poly silicon gates. A low-cost down-conversion method was used in this work to enhance the UV response of a CMOS image sensor. Vacuum thermal evaporation was used to deposit coronene films on quartz substrates and CMOS image sensors， respectively. The films'' optical characteristics，infrared spectrum，light stability，and thermal stability were investigated. The experimental results reveal that the Coronene coating absorbs UV light and emits green fluorescence at 500 nm，which closely matches the spectral response peak of the CMOS image sensor. At the same time，it is found that the experimental value of the infrared absorption spectrum of Coronene is in good agreement with the calculated value，and the fluorescence intensity of the emission peak remained 95.7% after the film was annealed at 200 ℃ for 20 minutes. After approximately 60 minutes of exposure at 280 nm excitation wavelength，the fluorescence intensity decreased exponentially to 64% of the initial value. The UV enhancement effect of the film was qualitatively analyzed by the CMOS monochromatic camera under visible light（400-780 nm） and ultraviolet light （365 nm） radiation. It is found that the sensitivity of the CMOS monochromatic camera to UV light can be improved after the deposition of Coronene film.