The invention discloses a laser sintering molding device. The laser sintering molding device comprises a molding shell, a support for dividing an inner cavity of the molding shell into an upper cavity and a lower cavity is arranged in the molding shell, the upper cavity is a closed cavity, and a preheater is installed on the side wall of the closed cavity; a laser penetrating window is installed at the position, over a molding chamber, of the upper surface of the molding shell, and a laser scanning head is installed over the laser penetrating window; and a portal frame is installed on the upper surface of the molding shell, and the laser scanning head is installed on the portal frame. The laser sintering molding device is simple in structure, reasonable in design and convenient to operate; under driving of a lower lead screw, the laser scanning head can move front and back, and under driving of an upper lead screw, the laser scanning head can move left and right; lasers emitted by a laser device are reflected by a galvanometer and focused by a varifocus lens, and formed laser beams penetrate the laser penetrating window to rapidly sinter powder of the molding chamber; and a hydraulic cylinder can drive the support to ascend and descend.