The invention relates to a mould kernel manufacturing method. The method comprises the following steps of providing a substrate; forming a thin film layer on one surface of the substrate; arranging a photoresist layer on the thin film layer; adopting a direct-write technique to expose the photoresist layer; and developing the photoresist layer so as to form a plurality of microstructures on the top surface of the photoresist layer and at least one hole which penetrates the photoresist layer, wherein due to the adoption of the hole, the thin film layer positioned under the photoresist layer is exposed; forming an electroforming layer on the surfaces of the microstructures by the exposed partial thin film layer in an electroforming way; removing the photoresist layer; separating the electroforming layer from the substrate; and removing the part of the electroforming layer formed inside the hole of the photoresist layer so as to obtain a mould kernel. The mould kernel is provided with a plurality of forming faces matched with the microstructures. The mould kernel manufacturing method lowers the surface roughness of the mould kernel.