The invention discloses a stair cavity mold production process. The process comprises the steps of discharging fixed mold workblank and a movable mold workblank; rough machining, tempering, finish machining and obtaining a movable mold and a fixed mold; forming a main mold cavity in the middle of the fixed mold workblank, forming an auxiliary mold cavity in the middle of the movable mold workblank, and drilling multiple through holes in the auxiliary mold cavity; discharging multiple I columns, carrying out heat treatment on the I columns, and fixing the I columns after heat treatment in the through holes; performing discharging and rough machining to obtain a main mold core blank part, carrying out further heat treatment and finish machining on the main mold core blank part, and obtaininga main mold core; assembling and fixing the main mold core in a main mold cavity of the fixed mold; and assembling the fixed mold and the movable mold, and enabling the I columns to be in abut jointwith the main mold core. Through machining of the fixed mold, the movable mold, the main mold core and the I columns, the fixed mold, the movable mold, the main mold core and the I columns are high inmachining precision, after heat treatment of the main mold core and the I columns, hardness is uniform, forming and demolding effect is good, and the casting quality can be improved.