Weeding device for grassland at lower side of expressway guardrail

The invention discloses a weeding device for grassland at the lower side of an expressway guardrail. The weeding device comprises a weeding machine body, sliding grooves are formed at the upper side of the weeding machine body in a bilateral symmetry manner, and a communication groove with a leftward opening is formed at the left side of the sliding groove at the left side; and a guide device comprises a belt wheel groove formed at the upper side of the sliding groove, a screwing block is screwed to adjust the position of a guide wheel, and therefore the purpose that the device can move forwards along with winding of the guardrail is achieved, and meanwhile when a cutting knife will touch the vertical guardrail, an infrared position sensor can recognize the position, the cutting knife moves upwards and then moves leftwards to retract into the machine body, after the cutting knife moves through the vertical guardrail, the cutting knife continues to weed, meanwhile, fan blades blow cut grass leftwards, and an a