Abstract: The pre-sintered 3D printed Al₂O₃ green body was subjected to pressure infiltration treatment with Al₂O₃ slurry, and then sintered. The effects of infiltration pressure and solid content of infiltration slurry on the relative density and compressive properties of ceramics were studied. The results show that the pressure infiltration significantly improved the relative density of 3D printed ceramics, and the greater the infiltration pressure, the greater the relative density of the green body. The relative density of the ceramic sintered samples with diameters of 1.0 cm and 1.5 cm gradually increased with the infiltrated slurry solid content, and the relative density of the ceramic sintered samples with a diameter of 2.0 cm increased first and then decreased. The infiltrating slurry with relatively low solid content was more helpful to increase the relative density of ceramic sintered samples with relatively large diameters, and the slurry with relatively high solid content was more suitable for ceramic samples with relatively small diameters. The bending strength of the 3D printed ceramics after infiltration was more than 10 times higher than that of uninfiltrated ceramics. As the solid content of the slurry increased, the bending strength of ceramic samples increased first. When the solid content (volume fraction) of the slurry reached more than 40%, the bending strength no longer changed significantly.