By　the　method　of　in-situ　synthesis　of　aluminum　nitride,　we　have　manufactured　AlN　powder　and　composite　AlN　powders　with　sintering　aids.　The　morphology　of　nitride　product　reveals　of　rod-like,　loose　and　parallel　structure.　The　average　particle　size　of　AlN　powder　is　6.78　μm　and　its　distribution　shows　a　double-peak　curve.　To　illustrate　the　nitridation　process,　the　mass　transfer　model　was　constructed,　and　the　mass　transfer　equations　were　established.　Furthermore,　the　conclusion　has　been　drawn　that　the　diffusion　of　N　atom　is　the　key　factor.