We hereby introduce an air-conditioning system which uses a nano-photocatalyst sterilization device. The system consists of a base, a cover, a photocatalyst filter, a kit, a packing piece and a number of lighting devices. This assembles into a sterilization device which installs
into an air conditioning system. The lighting device is composed of a circuit base with a bowl-shaped casing and a high-powered LED light source, the inner wall of the bowl casing is shaped into a hood-like projection area. By the use of high-powered LED light source and a bowl-shaped casing, a varnish design is formed. This results in the light projections from the LED light source to refract and collide inside the projection area of the bowl-casing to achieve even exposure of the photocatalyst filter, enhancing lighting density, illumination and utilization to remove toxic bacteria, toxic gases, odors and pollutants further improving indoor air quality.