Hydroxyapatite　(HA)　coatings　were　prepared　on　Ti-6Al-4V　substrate　by　using　the　method　of　microplasma　spraying.　Commercially　pure　argon　gas　and　helium/argon　(50%　in　volume)　mixed　gas　were　used　as　working　gas　in　the　spraying　processing　respectively.　The　surface　morphology,　phase　compositions　and　degree　of　crystallinity　of　the　coatings　were　examined　by　scanning　electron　microscope　(SEM)　and　X-ray　diffraction　(XRD).　Results　show　that　less　impurity　phases　and　no　TTCP　and　CaO　phases　were　found　in　the　coatings.　The　crystallinity　of　coatings　is　higher　than　70%,　which　is　beneficial　for　implantation　materials　stability　in　vitro　and　vivo.　The　enthalpy　of　microplasma　arc　in　which　helium/argon　mixed　is　used　as　working　gas　is　higher　than　that　in　which　commercially　pure　argon　gas　is　used.　The　crystalline　phases　in　the　former　coatings　mainly　consist　of　recrystallization　grains　while　the　latter　coatings　were　mainly　made　up　of　lots　of　unmelted　HA　particles.