In　this　study,　high-strength　and　wave-transmission　silicon　nitride　(Si3N4)　composites　were　successfully　developed　via　selective　laser　sintering　(SLS)　with　cold　isostatic　pressing　(CIP)　after　debinding　and　before　final　sintering,　and　the　optimal　moulding　process　parameters　for　the　SLS　Si3N4　ceramics　were　determined.　The　effects　of　the　sintering　aids　and　secondary　CIP　on　the　bulk　density,　porosity,　flexural　strength,　fracture　toughness,　and　wave-transmitting　properties　of　the　Si3N4　composites　were　studied.　The　results　showed　that　the　increased　CIP　pressure　was　beneficial　to　the　densification　of　SLS　Si3N4　ceramics　and　improved　their　mechanical　properties.　However,　the　wave-transmitting　performance　decreased　as　the　CIP　pressure　increased.　The　Si3N4　ceramics　prepared　by　the　moulding　of　sample　S11　were　more　in　line　with　the　performance　requirements　of　the　radomes.　To　obtain　good　comprehensive　performance,　an　additional　3%　of　interparticle　Y2O3　was　added　to　the　pre-printed　mixed　powder　of　granulated　Si3N4　particles　and　resin　and　the　secondary　CIP　pressure　was　adjusted　to　280　MPa.　After　sintering,　the　bending　strength,　fracture　toughness,　and　dielectric　constant　of　the　Si3N4　ceramics　were　651　MPa,　6.0　MPa　m1/2,　and　3.48　respectively.　This　study　provides　an　important　method　for　preparing　of　Si3N4　composite　radomes　using　SLS　process.　©　2022　Elsevier　Ltd　and　Techna　Group　S.r.l.