Sodium　ion　batteries　(SIBs),　which　share　a　similar　electrochemical　reaction　mechanism　to　lithium　ion　batteries　(LIBs),　have　already　attracted　much　attention　because　of　the　rich　reserves　and　low　cost　of　sodium.　TiO2　is　considered　as　one　of　the　promising　anodes　for　sodium　ion　batteries　due　to　its　large　sodium　storage　capacity　and　potentially　low　cost.　However,　low　electrical　conductivity　limits　the　wide　application　of　TiO2　for　sodium　ion　batteries.　Here　nitrogen　doped　TiO2　(N-TiO2)　nanoparticles　are　prepared　via　nitrogen　plasma　treatment　and　investigated　as　anode　materials　for　sodium　ion　batteries.　The　N-TiO2　nanoparticles　demonstrate　a　much　better　rate　performance,　yielding　discharge　capacities　of　about　621　mA　h　g(-1)　at　0.1C　and　75　mA　h　g(-1)　at　5C　(1C　=　335　mA　h　g(-1)),　and　a　clearly　enhanced　capacity　retention　(more　than　98%　after　more　than　400　cycles)　compared　with　those　of　pristine　TiO2.　What　is　different　from　the　other　nitrogen　doped　TiO2　reported　in　the　literature　is　that　a　disordered　surface　layer　with　a　thickness　of　around　2.5　nm　is　formed　on　the　N-TiO2　nanoparticles　after　N-2　plasma　treatment,　which　is　barely　found　in　normal　nitrogen　doping　processes.　Both　the　doped　nitrogen　and　the　disordered　surface　layer　play　significant　roles　in　enhancing　the　sodium　storage　performance.