The　properties　and　performances　of　plasma　spray　coatings　depend　on　the　coating-substrate　interface　adhesion　and　the　splat-splat　interface　cohesion.　Oxidation　during　atmospheric　plasma　spraying　of　metal　alloy　affects　significantly　the　coating　cohesion.　In　this　study　stainless　steel　splats　were　deposited　on　the　preheated　stainless　steel　substrate　with　the　oxide　scale　of　different　thicknesses　in　inert　low　pressure　plasma　spay　(LPPS)　condition　to　examine　the　effect　of　in-situ　oxidation　of　previous　splat　during　spraying　on　the　morphology　of　the　later　splat　and　splat　bonding　formation.　The　stainless　substrate　was　preheated　to　350　°C　before　splat　deposition.　The　cross　sections　of　splat-substrate　interface　were　prepared　by　focus-ion-beam　(FIB)　processing.　The　splat　morphology　and　splat-substrate　interface　bonding　state　were　characterized　by　scanning　electron　microscopy　(SEM).　Results　show　that　with　the　oxide　films　up　to　35　nm　thick,　the　disk-type　splats　are　deposited,　which　bond　to　the　oxidized　substrate　well　at　most　splat　interface　except　the　periphery　region.　When　oxide　scale　becomes　~100　nm　thick　and　presents　a　micrometer　rough　surface,　the　splats　present　fingering　shape　without　any　effective　bonding　at　the　interface.　Therefore,　it　is　clear　that　the　effect　of　the　oxide　on　substrate　surface　on　splat　morphology　and　splat　bonding　formation　depends　on　the　thickness　and　surface　morphology　of　oxide.