A metal casting fabrication method is provided. In accordance with the method, first a metal plate is disposed in the cavity of molding dies. This metal plate includes a first surface formed with a heat insulating layer, and a second surface opposite to the first surface. With the metal plate placed in the cavity, the heat insulating layer is held in contact with the dies, while the opposite or second surface is partially exposed to the cavity. The injected molten metal properly fills the cavity from end to end since its heat is not conducted unduly to the dies via the metal plate.