The utility model relates to a hydraulic rapid locking device for a ring rolling mill main roller box. The hydraulic rapid locking device for the ring rolling mill main roller box is characterized in that the two side faces of a roller box bottom board are slopes, a locking oil cylinder is installed behind a fixing beam, a piston rod extends out of the front of the fixing beam, the front end of the piston rod is sleeved with a movable wedge block, the movable wedge block is installed on one side face of the main roller box bottom board, and a fixed wedge block is installed on the other side face of the roller box bottom board. The hydraulic rapid locking device has the advantages that the main roller box is rapidly locked and loosened through a hydraulic cylinder and can be conveniently and rapidly installed and detached.