The utility model discloses a disc casting molding device. The disc casting molding device comprises an inner pouring gate communicated with a casting cavity of a disc casting, and an air outlet risercommunicated with the interior of the casting cavity is arranged at the top of the casting cavity. The gas outlet riser is of a vertically-through circular-truncated-cone-shaped structure, and the top of the circular-truncated-cone-shaped structure is larger than the bottom of the circular-truncated-cone-shaped structure. And one end of the flow gate is communicated with the casting cavity, and the other end of the flow gate is communicated with the slag collecting ladle nest. And the slag collecting ladle nest is of a hollow arched flat bottom structure. The top of the slag collecting ladlepit is communicated with a slag collecting riser, and a filter screen is arranged between the slag collecting ladle pit and the slag collecting riser. The filter screen is a ceramic filter screen, andthe ceramic filter screen is of a cylindrical structure. And in combination with other structures, the defects that in the prior art, the technological yield of castings produced by casting disc castings is about 50%, sand holes, slag holes and air hole surface casting defects are prone to occurring on the top plane of a casting cavity, and the production efficiency and quality cannot meet the requirements easily are effectively avoided.