The invention provides a folding and unfolding device of a vertical pipeline sandblast to overcome the problem that as a vertical pipeline of a process pipeline of a seawater cooling system of a nuclear power station is fixed on a wearing floor and a steel structure rack and cannot move, anticorrosion maintenance cannot be carried out on the inner wall of the vertical pipeline. The folding and unfolding device comprises a motor (1), a gearbox (2), a manual control device (9), a rope folding and unfolding device of a sandblast (5), a bearing bracing frame (6), tension wheels on one side (4), and tension wheels on the other side (10), wherein the motor (1) drives a main shaft (3) to rotate, the rope folding and unfolding device of the sandblast (5) is installed on the main shaft (3), the tension wheels on one side (4) and the tension wheels on the other side (10) disposed on both sides of the rope folding and unfolding device of the sandblast (5) respectively on the main shaft (3) can rotate with the main shaft (3), and the rope on the rope folding and unfolding device of the sandblast (5) is connected with the sandblast. The folding and unfolding device of the vertical pipeline sandblast can improve work efficiency greatly, guarantee construction quality, and improve safety factor.