Understanding the spatial curing growth mechanism and defect formation of green bodies is of great significance for the manufacture of precision and high-performance ceramic products. In this work, the effects of different powder volume fractions and average particle sizes on the spatial curing growth mechanism and defect regulation of alumina green bodies in stereo-lithography were discussed by combining novel mathematical theories and experiments. We found the spatial curing growth characteristics and defect shapes of green bodies in the mathematical model, and obtained the distribution patterns of the beam zone, scattering zone, inadequate curing area and overlap area, as well as their relationship with defect evolution. Furthermore, we verified these characteristics of green bodies through experiments and found that these characteristics could be improved by the most optimal experimental parameters based on mathematical theories. In particular, the print layer thickness could selectively modify the curing shape and improve the printing condition.