The invention discloses a spraying device used for an asphalt pavement regeneration protective agent in a laboratory. The spraying device comprises a conveying pump, a raw material barrel, a square plate atomizing sprayer, a control box, a sliding rail device and a spraying chamber provided with a spraying chamber door. The conveying pump is connected with the raw material barrel and the square plate atomizing sprayer through pipelines respectively. The pipeline between the conveying pump and the raw material barrel is provided with an electric valve. The square plate atomizing sprayer is embedded in the center of the top in the spraying chamber. The sliding rail device is transversely arranged in the middle of the bottom in the spraying chamber. The control box is connected with the conveying pump, the electric valve and the spraying chamber through circuits. The invention further provides a control method of the spraying device. A sliding rail and a spraying system are combined, the asphalt pavement regeneration protective agent is evenly sprayed on the surface of an asphalt mixed material to form a sealed interface, the protective agent is fully and evenly dispersed, performance of an asphalt pavement surface is improved, and pavement performance of an asphalt pavement regeneration protective agent material can be better evaluated.