Background:　Hydroxyapatite/polymer　composite　materials　have　been　widely　reported　as　tissue　engineering　materials;　however,　they　are　limited　in　repairing　treatment　because　of　the　powder　or　piece　in　shape.　Objective:　To　prepare　the　nanohydroxyapatite　(HAP)/chitosan-gelatin　(CG)　composite　microspheres,　and　to　observe　the　general　drug　release　in　vitro.　Design　Time　and　Setting:　Repeated　measurement　study　was　performed　at　Laboratory　of　Biological　Functional　Polymer,　College　of　Material　Science　and　Chemical　Engineering,　Beijing　University　of　Technology　between　January　and　October　2008.　Materials:　Nanohydroxyapatite,　chitosan,　gelatin,　and　gentamicin　were　used　in　this　study.　Methods:　Microwave　irradiation　method　was　used　to　synthesize　aciform　hydroxyapatite　(pH=7),　and　W/O　combined　with　multiple　emulsification　chemical　crosslink　technique　was　used　to　prepare　nanohydroxyapatite/　chitosan-gelatin　composite　microspheres.　Main　Outcome　Measures:　1　Surface　morphology　and　particle　diameter　distribution;　2　drug　loading,　entrapment　efficiency,　and　cumulative　release　rate.　Results:　(1)　The　composite　microspheres　were　spherical　in　shape,　and　the　particle　diameter　ranged　from　10　to　30　μ　m.　Hydroxyapatite　was　greatly　embedded　by　chitosan-gelatin.　2　The　average　drug　loading　was　32.97%,　the　average　entrapment　efficiency　was　49.20%,　and　the　cumulative　release　rate　to　gentamincin　was　near　88%　within　3　days.　Conclusion:　The　composite　microspheres　exhibit　well-distributed　morphology,　narrow　particle　diameter　distribution　and　good　redispersibility.　They　can　maintain　an　therapeutic　concentration　within　3　days.