With the continuous development of science and technology, Si₃N₄ ceramics are playing an increasingly important role in high-tech fields such as aviation machinery, biology and medical treatment. In this work, Si₃N₄ ceramics were successfully prepared by digital light processing (DLP) technology using Si₃N₄ powder coated with Al₂O₃-Y₂O₃ as raw material. Effects of solid loading of slurry on the performance of Si₃N₄ ceramic slurry, Si₃N₄ ceramic green parts and Si₃N₄ ceramics were systematically studied. The results showed that when the solid loading of slurry was less than 40.0% (in volume), its viscosity was less than 2 Pa·s at shear rate of 30 s^-1, which can be used for DLP forming. In that case, the single curing depth of the slurry decreased with the increase of solid loading of the slurry, while the relative density and flexural strength of Si₃N₄ ceramics formed by DLP increased firstly and then decreased. The relative density and flexural strength reached the maximum of 89.8% and 162.5 MPa at solid loading of 37.5% (in volume), which were 10% and 16% higher than those with solid loading of 32.5% (in volume), respectively. In this work, the properties of Si₃N₄ ceramics formed by DLP were optimized by determining the best solid loading, which laid the experimental foundation for the photocuring of non-oxide ceramics such as Si₃N₄.