An illuminating warning lamp includes a first light source and a second light source assembled on a lamp socket. An irradiation direction of the first light source and that of the second light source form an angle of 90 degrees with respect to each other. Additionally, a first lamp casing for encapsulating the first light source is further formed with a through hole at one side thereof, and a second lamp casing corresponding to the second light source is assembled within the through hole. After the first and second light sources are both driven to emit lights, the lamp simultaneously emits warning lights and illumination light.