Vat　photopolymerization　3D　printing　provides　a　novel　approach　for　preparing　broadband　wave-transparent　Si3N4/β-SiAlON　composite　ceramics.　This　paper　oxidized　raw　powder　to　introduce　low　dielectric　phases　(SiO2)　and　overcome　the　low　curing　depth　of　α-Si3N4.　The　solid　content　of　oxidized　α-Si3N4　was　increased　to　50　vol%　for　the　first　time　by　modification　with　dispersant.　The　selected　print　thickness　of　50　μm　was　the　highest　known　for　Si3N4　vat　photopolymerization　3D　printing,　greatly　improving　printing　efficiency.　Finally,　Si3N4/β-SiAlON　composite　ceramics　were　sintered　in　the　range　of　1600-1800　°C,　and　the　mechanical　and　dielectric　properties　were　systematically　studied.　The　composite　ceramics　sintering　at　1780　°C　had　a　maximum　bending　strength　of　236　±　16　MPa,　and　the　real　permittivity　was　4.83.　At　1800　°C　the　porosity　increased　resulting　in　bending　strength　decreased　to　109　±　4　MPa,　and　the　real　permittivity　to　3.23.　This　study　filled　the　gap　in　the　post-treatment　of　oxidized　α-Si3N4　and　guided　the　application　of　Si3N4/β-SiAlON　composite　ceramics　in　the　field　of　wave-transparent.　©　2024