The invention relates to a spraying device of an automatic pesticide sprayer for a vineyard, and aims to solve the problem of non-uniform manual spraying of pesticides. The spraying device comprises two supporting frames, a guide rail, a slide block, a spray nozzle, a pesticide bucket, a water pump, a pesticide tube, a tube reel, a handle, a line reel, a pull rope and a rotary motor, wherein the supporting frames are positioned at the left and right ends of a grape trellis respectively; the guide rail is fixedly connected between the two supporting frames; the slide block is arranged on the guide rail; the spray nozzle is detachably arranged on the slide block; the water pump is arranged on the pesticide bucket; one end of the pesticide tube is connected with the spray nozzle, and the other end of the pesticide tube is connected with the water pump; the tube reel is used for winding the pesticide tube and is positioned at the right end of the grape trellis; the handle is arranged on the tube reel; the line reel is adapter-coupled to the supporting frame on the left side of the grape trellis; the pull rope is connected to the line reel in a winding manner and is connected with the slide block; the rotary motor is connected with the line reel; a sliding chute which is matched with the slide block is formed below the guide rail; a slot is formed below the sliding chute; the spray nozzle is positioned in the slot. By adopting the machine to spray, uniform spraying is realized, the resource is saved, the working efficiency is high, the cost is low, the sprayer is suitable for large-area pesticide spray, and the labor is saved.