The utility model provides a continuous casting ladle long water gap mechanical arm. The continuous casting ladle long water gap mechanical arm can realize horizontal movement in the front and back direction and the left and right direction, can control a water gap to lift, and compress or depart a ladle through a hydraulic system, can follow the ladle, can be always stable, and can control the water gap to rotate clockwise or counterclockwise. The mechanical arm mainly comprises a supporting post, a rotating arm, a bracket, a long working arm, a hydraulic cylinder and the hydraulic system, wherein a rotating shaft at one end of the rotating arm is connected with the supporting post, and the rotating arm can rotate around the supporting post; a rotating shaft at the other end of the rotating arm is connected with the bracket, and the bracket can rotate around the axis of the rotating shaft; the long working arm is hinged to the bracket through a middle hinging shaft on the long working arm; a middle hinging shaft or a tail end hinging hole of the hydraulic cylinder is hinged to the bracket; an extending rod of the hydraulic system is hinged to the long working arm; when the hydraulic cylinder extends and retracts, the long working arm swings up and down around the middle hinging shaft on the long working arm; a hand wheel rotating mechanism is arranged at the rear end of the long working arm, so that the mechanical arm, i.e. a water gap fork head, mounted at the front end of the long working arm is enabled to rotate clockwise or counterclockwise.