The work aims to study the effects of hydroxyapatite (HA) particle size on the splat morphology and coating mi-crostructure 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 ana-lyzed. 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 for-mation 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 de-composed phases with less preference in orientation.