A　novel　composite　powder　preparation　technology　based　on　selective　reaction　in　solid　solution　was　studied.　The　principle　of　thermodynamics　was　utilized　to　calculate　the　selective　nitridation　conditions　with　ammonia　in　a　t-ZrO2-TiO2　solid　solution　system.　The　influence　of　reaction　temperature　on　the　phase　structure　was　investigated.　Titanium　nitride　was　synthesized　by　ammonia　reduction　and　nitridation　under　flowing　ammonia　atmosphere　while　the　content　and　tetragonal　phase　structure　of　zirconia　was　unchanged.　The　average　particle　size　and　morphology　of　nanopowders　before　and　after　nitridation　were　characterized　by　specific　surface　area　measurement　and　transmission　electron　microscopy.　The　particle　size　of　t-ZrO2　is　about　50-70　nm　in　the　composite　powders　after　nitridation.　Elemental　quantitative　analysis　indicates　that　the　nitridation　ratio　reaches　98%.