The invention discloses a reversely graved three-dimensional head portrait manufacturing method which comprises the steps of head portrait preparation, blank preparation, impression, deep graving and engraving, reverse female die manufacturing, grouting, air exhausting, condensation molding, coloring, coating and the like. The method specifically comprises the followings steps of: impressing a concave head portrait on an oil blank material; deepening the lines of the concave head portrait by using a graver, wherein the engraved lines are deepened by 3-8% compared with the original lines; manufacturing a model, injecting molding rubber in the model provided with the model, and inverting the female die of the head portrait; and injecting glass slurry for condensation molding after opening the female die, and coloring and coating the molded blank to obtain the finished product. The invention enables the concave head portrait to achieve the convex three-dimensional head portrait effect toward the direction opposite to the concave by using spatial fluctuations and human visual illusion through the methods of reversely graving the concave head portrait and deepening graving depth, and thus, the head portrait is life-like and vivid.