The invention discloses a full-size crab binding device. The device comprises a base plate, a front baffle, a rear baffle, a front guide rail, a rear guide rail, a right baffle and a left baffle, wherein at least one of the front baffle and the rear baffle is arranged on the base plate in a sliding mode, and openings are formed in the front baffle and the rear baffle respectively and penetrate through the upper portion of the front baffle and the upper portion of the rear baffle; the front guide rail is arranged at the two ends of the front baffle, and the rear guide rail is arranged at the two ends of the rear baffle; one end of the right baffle and one end of the left baffle are arranged on the front guide rail in a sliding mode, and the other end of the right baffle and the other end of the left baffle are arranged on the rear guide rail in a sliding mode. The device further comprises a positioning device arranged on the front baffle or the rear baffle. Due to the fact that the front baffle, the rear baffle, the left baffle and the right baffle are movably arranged, the crab fixing position can be flexibly adjusted according to the size of a crab, the baenopoda of the crab is made to be right located on the openings in the front baffle and the rear baffle, ropes for binding the crab are arranged at the positions of the openings, and then the crab can be bound conveniently through the ropes.