The invention discloses a door frame and further discloses a molding press door and a preparation method of the molding press door. The door frame comprises a door frame main body and a side frame. Arectangular opening with the size being matched with that of a rectangular door core is formed in the middle of the door frame main body, and a rectangular right-angle groove surrounding the rectangular opening is formed in the obverse side of the door frame main body. The cross section of the right-angle groove is in an L shape, and the right-angle groove comprises a horizontal groove face parallel to the obverse side of the door frame main body and a vertical groove face perpendicular to the obverse side of the door frame main body. The horizontal groove face is covered with the side frame,and the side frame extends out of the horizontal groove face towards rectangular opening to form an abutting-joint part. The thickness of the side frame is smaller than or equal to the height of the vertical groove face. The molding press door formed by assembling the door frame is overall flat and smooth, the stability and strength of the molding press door are enhanced, and the impact-resistantand extruding-resistant properties of the molding press door are also enhanced.