The invention discloses a blast furnace slag liquid face crusting breaking device, and relates to the technical field of chemical metallurgical. The problems that a crane or electric block is used forlifting a heavy hammer for slag breaking, the slag breaking position is not accurate, residue bonded on the heavy hammer cannot be cleaned, and slag breaking force is not enough are solved. Accordingto the technical scheme, the blast furnace slag liquid face crusting breaking device comprises a supporting frame, guide rods, a heavy hammer and a slag cleaning plate; a slag breaking platform is arranged on stand columns of the supporting frame, the guide rods are arranged on the slag breaking platform, a transverse connecting rod is arranged on the guide rods in a penetrating manner, a heavy hammer connecting rod and a slag breaking oil cylinder are connected to the transverse connecting rod, the slag breaking oil cylinder is used for pushing the heavy hammer to carry out slag tank liquidface crusting breaking, due to the fact that the heavy hammer is in rigid connection, pressure can be applied through the slag breaking oil cylinder, the slag breaking force can be improved, and the accurate slag breaking position is ensured. The slag cleaning plate is arranged on the slag breaking platform, and can be controlled through the slag cleaning oil cylinder, blast furnace slag remainingon the heavy hammer can be removed, and the blast furnace slag liquid face crusting breaking device is easy and convenient to operate, simple in structure and beneficial for maintaining and overhauling.