In a LED warning light, straight light units are fixed to straight peripheries of a warning light body, and curved light units are fixed to joints adjacent to two respective straight peripheries. Each straight light unit includes a light base, a reflective plate, a heat dispersion cover and a front cover. LED lights are arranged on the light base. The front cover is perpendicular to the light base opposite to the reflective plate. The reflective plate has light reflective elements connected to each other in a straight line. Light rays emitted from the LEDs are reflected by the reflective plate and then given off perpendicularly to the front cover. The vertical distance from an upper periphery of the arc top of the light reflective element to the corresponding inner surface of the heat dispersion cover is more than or equal to zero.