Al2O3-TiO2-ZrO2-CeO2　coatings　formed　via　a　plasma　spray　approach.　The　optimal　spray　parameters　of　plasma　sprayed　nano-structured　coating　were　determined　by　orthogonal　experimental　design,　based　on　porosity,　bond　strength　of　the　coatings　and　the　partly　melted(PM)　zone　percentage.　Microstructure　of　the　plasma　sprayed　nanostructured　Al2O3-TiO2-ZrO　2-CeO2　coating　sprayed　on　the　optimal　spray　parameters　was　analyzed.　Wear　map　was　established　by　wear　experiments.　The　results　show,　nanostructured　coating　contains　fully　melted　(FM)　zone　and　PM　zone,　the　increasing　of　the　critical　plasma　spray　parameter　(CPSP)　promote　the　decreasing　of　the　PM　zone　percentage　and　the　increasing　of　the　bond　strength　of　the　coatings.　The　composition　phases　of　the　powder　reacted　to　each　other　during　the　plasma　spraying　process.　FM　and　PM　zone　resulted　from　fully　melted　droplets　and　partly　melted　particles　respectively.　Nanosized　crystals　and　amorphous　particles　exist　in　the　PM　zone,　liquid　phase　sintering　is　taken　place　in　the　PM　zone.　The　main　wear　mechanism　of　plasma　spraying　coatings　are　plastic　deformation　and　microplow,　microfracture　and　grain　spalling,　fracture　and　delamination　at　different　normal　load　and　sliding　speed　in　dry　friction.　©　(2011)　Trans　Tech　Publications,　Switzerland.