A high power light string device comprises a plug with a plug blade set, a tail receptacle, and at least an LED string, wherein a first power adaptor disposed in the plug converts an AC voltage through the plug blade set to a high DC voltage, and a second power adaptor disposed in the tail receptacle converts the AC voltage through the plug blade set to a low DC voltage. Two ends of the LED string are respectively connected to the first and second power adaptors to receive the high and lower DC voltages so that the LED string is turned on to emit light. The power adaptors are directly disposed respectively in the plug and the tail receptacle to simplify the whole light string device so as to enhance the decorating effect of the light string device.