Hydraulic locking mechanism, opening and closing method and helicopter

The invention discloses a hydraulic locking mechanism, an opening and closing method and a helicopter. The hydraulic locking mechanism comprises a support and a sling connector; a piston cylinder is slidably connected into the support, a first protruding plate is arranged on the side face of the piston cylinder, a second protruding plate is arranged on the inner wall of the support, the first protruding plate is located above the second protruding plate, a sealed oil cavity is formed by the outer side, above the first protruding plate, of the piston cylinder and the inner wall, above the second protruding plate, of the support, and the oil cavity communicates with a hydraulic valve; two lock catches are hinged to the interior of the support and both located in the piston cylinder, protruding blocks are arranged on the opposite faces of the two lock catches, the sling connector is located between the two lock catches, and a boss is arranged at the top of the sling connector; when the piston cylinder is located