The furnace body is a cover, or the furnace bottom does not move, the furnace cover moves, or the furnace cover does not move, the furnace bottom moves heat treatment furnace. Used for batch heat treatment of workpieces. The mask annealing method has better quality and higher efficiency than the traditional annealing method. The workpiece is treated by recrystallization nodular annealing to reduce the hardness of the workpiece, eliminate cold work hardening and restore the plastic deformation ability of the workpiece. When annealing, the workpiece is placed on the furnace, buckle the protective cover (that is, the inner cover), the protective cover through the protective gas, and then buckle the heating cover (that is, the outer cover), heating to a certain temperature and then cooling. A protective atmosphere is used during annealing to prevent oxidation and decarbonization of the workpiece, so that the lubricant on the surface can be more easily evaporated and better mechanical properties can be obtained.