The　work　aims　to　study　the　effects　of　hydroxyapatite　(HA)　particle　size　on　the　splat　morphology　and　coating　microstructure　during　micro-plasma　spraying.　Three　groups　of　HA　particles　with　different　sizes　(25~38　μm,　38~45　μm,　45~63　μm)　were　selected　and　the　splat　particles　were　collected　on　the　bright　finished　Ti-6Al-4V　substrates　and　then　adopted　to　deposit　HA　coatings　on　sandblasted　Ti-6Al-4V　substrates　by　micro-plasma　spraying　method.　The　morphologies　of　splat　and　coatings　were　observed　by　cold　field　emission　scanning　electron　microscopy　(SEM).　The　phase　composition　and　preferred　orientation　of　the　as-sprayed　coatings　were　analyzed　through　X-ray　diffraction　(XRD).　The　three-dimensional　morphology　characteristics　of　HA　splats　were　observed　by　laser　scanning　confocal　microscope　(LSCM)　and　the　difference　between　splats　was　compared　and　analyzed.　Splats　formed　during　micro-plasma　spraying　showed　distinct　morphology　characteristics:　(i)　Oblate　spheroid　with　thicker　central　area　and　thinner　edge　areas;　(ii)　Disk　shaped　splats　with　thinner　central　area　and　thicker　edge　areas,　exhibiting　a　thinner　thickness　and　a　larger　average　diameter　compared　with　oblate　shaped　splats;　and　(iii)　Disk　shaped　splats　with　finger　splashing　at　the　rim,　having　a　larger　diameter　but　thickness　as　same　as　the　disk　shaped　splats.　With　the　decreasing　particle　sizes,　both　the　crystallinity　and　texture　intensity　of　the　coatings　decreased,　while　the　tendency　of　HA　decomposition　and　amorphous　phase　formation　increased.　Meanwhile,　the　preferred　orientation　intensity　and　the　ratio　of　columnar　grains　decreased.　The　morphology　of　the　collected　splats　and　as-sprayed　coatings　was　strongly　influenced　by　the　particle　sizes　during　micro-plasma　spraying.　As　the　particles　sizes　increase,　the　splat　morphology　was　transformed　from　the　oblate　spheroid　into　the　disk　shape　with　a　small　amount　of　splashing　at　the　rim.　The　melting　degree　of　the　fine　powders　were　better,　so　the　coatings　contained　more　amorphous　and　decomposed　phases　with　less　preference　in　orientation.　©　2019,　Chongqing　Wujiu　Periodicals　Press.　All　rights　reserved.