Plasma spraying was used to deposit Li3PO4 for the applications to all-solid-state lithium battery (ASS-LB) electrolyte. Sintered dense powder was used for plasma spraying in three different size ranges. The effects of powder particle size and spray distance were investigated on the deposit composition and microstructure. The microstructure; crystal structure and composition of the Li3PO4 deposit were characterized using SEM; XRD; ICP-MS and FTIR. The result shows that the sintered dense Li3PO4 powders present a high temperature orthorhombic phase γ-Li3PO4; being different from β-Li3PO4 of agglomerated Li3PO4. Plasma-sprayed Li3PO4 coating presents a dense microstructure with a similar fractured surface morphology to that of sintered bulk. The coating retains the phase structure of the sintered powder. The atomic ratio Li/P of plasma-sprayed Li3PO4 deposits increased with the increase of the spray distance in a range of 3.02-3.16; being a little larger than the stoichiometric ratio of Li3PO4. The deposit by the smaller powders than 30 μm exhibits a higher Li/P ratio of 3.16.