Casting coating method

The invention discloses a casting coating method. Equipment adopted in the method comprises a casting mold, a pressing plate and a limiting block. A liquid injection hole is formed in the center of the bottom of the casting mold; and the limiting block is fixed to the middle of the lower end face of the pressing plate. The method comprises the steps that the upper end face of a grain is bonded to the lower end of the limiting block, and the upper end of the casting mold is covered with the pressing plate in a pressed manner; an organic glass coating agent is poured into an inner cavity of the casting mold from the liquid injection hole at the bottom of the casting mold under the condition that the lower plate surface of the pressing plate is kept in contact with the upper edge of the casting mold; when the liquid level of the organic glass coating agent rises to be flush with the upper end face of the cylindrical grain, the liquid injection hole at the bottom of the casting mold is sealed; and after the organ