The invention specifically relates to an automatic forming method for a UO2 fuel pellet blank applied to a low-enrichment miniature neutron source reactor, belonging to the technical field of fuel pellets for low-enrichment miniature neutron source reactors. The automatic forming method comprises the following steps: briquetting UO2 powder, then crushing the briquetted UO2 powder with a granulator, and carrying out sieving with a screening machine so as to obtain UO2 powder with a particle size of 100 to 500 [mu]m; adding a lubricant accounting for 0.1 to 0.5 wt% of the mass of the UO2 powderand carrying out uniform mixing; carrying out fuel pellet forming with a mechanical press, wherein the height and density of the fuel pellet blank are controlled to be 4 to 7 mm and 5.2 to 5.4 g/cm<3>, respectively; and subjecting a formed fuel pellet to reductive sintering in a hydrogen atmosphere, wherein the sintering of the UO2 fuel pellet belongs to solid-phase sintering. The automatic forming method improves forming efficiency by three times or more and has substantial effect; and due to accurate control of forming, accurate control of size can be realized without grinding, the indexes of size, density and the like all meet technical index requirements, and the utilization rate of materials is improved.