Abstract: An improved structure of reflective warning triangle which has many holes inside the triangle for plugging in the bright red LED's, said reflective warning triangle having a reflecting plate and a transparent plate together. Said reflective warning triangle has tight washers to seal the holes containing the LED's to achieve the goal of a water-proof device. The LED's are series-parallel connected six by six so as to keep the reflective warning triangle of the present invention shining even when part of the circuit is short-circuited.