Provided are a system and process for remanufacturing a waste cylinder assembly of an aircraft piston engine. The spraying apparatus includes a first power mechanism, a spray gun assembly and a second power mechanism. The first power mechanism drives the cylinder assembly to move in a horizontal direction and a vertical direction. The second power mechanism drives the spray gun assembly to rotate around a center of the blind hole and ensures that prepared coatings can be evenly distributed along an inner wall of the blind hole. A nozzle end of the spray gun extends into the blind hole, and the spray gun is adjustable relative to the center of the blind hole. A spraying distance is not fixed so as to change the spraying distance. Powder can be fully melted.