An LED light source module includes a base, an LED light source positioned on the base, an optical lens located on the light path of the LED light source and a diffusion plate positioned above the optical lens. An upper surface of the base is a light reflective surface. The optical lens defines a through hole aligned with the LED light source. A reflecting body is protruded from the diffusion plate toward the through hole of the optical lens. When the light emitted from the LED light source is projected to the reflecting surface of the light reflecting body through the through hole, the light is reflected by the reflecting surface to reach the upper surface of the base, and then is reflected by the upper surface of the base to reach the diffusion plate.