A microfabrication process for making a microstructure product comprises: micromachining a polymer substrate for forming a three-dimensional microstructure pattern with deep cavities; shrinking and minimizing the diameter or width of each cavity of the microstructure pattern by steadily swelling the polymer, which is prefixed on a cathode of an electroforming system, by saturating the electrolyte solution into the polymer; electroforming in the electroforming system electrically connected with an anode and the cathode for filling metal in the cavities in the polymer; and desorption of the electrolyte from the polymer to shrink the polymer to be separated from an electroformed microstructure product, and demolding for obtaining the microstructure product having a high aspect ratio of 100 or even higher. The diameter or width of each cavity is shrunk to be smaller, thereby increasing the aspect ratio of the microstructure product.
