A reflective rear light for a truck includes a light housing, a reflection plate and a lens. The light housing is formed integrally with a circuit board provided thereon with a clearance light and side marker light region. The reflection plate is provided with a side reflecting plate corresponding to the clearance light and side marker light region on the circuit board. The lens has one side disposed with a side light transmission region having its front side provided with a clearance light refraction region, having one inner side equipped with a slot at a location near the side light transmission region for fitting a side reflector with a side light refraction region. The truck rear light is disposed with several different warning light regions to illuminate a license plate and reinforcing effect of projecting light on the truck width and side.