Sodium-ion　batteries　have　emerged　as　a　desired　alternative　to　lithium-ion　batteries　(LIBs)　on　account　of　their　low　cost,　good　safety,　and　large　reserves　of　sodium　in　the　earth＇s　crust.　The　sodium　storage　capabilities　of　batteries　significatnly　depend　on　the　structure　and　composition　of　electrode　materials.　Herein,　a　new　type　of　C,N-codoped　MoS2　nanoonions　with　ultralarge　interlayer　spacing　of　1.16　nm　has　been　successfully　fabricated　by　vapor　phase　sulfuration　of　the　as　prepared　PPy-PMo12　precursor　at　an　optimized　vulcanization　temperature.　More　importantly,　the　delicate　internal　nanostructure　has　been　directly　observed　via　electron　tomography　(ET)　technique　and　3D　reconstruction.　Thanks　to　the　structure　and　composition　merits,　the　resulting　anode　materials　of　C/N-MoS2-800　delivers　remarkable　sodium　storage　properties.　The　reversible　capacity　retains　617.7　mA　h　g(-1)　at　100　mA　g(-1)　after　200　cycles.　The　electrochemical　kinetic　analysis　and　density　functional　theory　(DFF)　calculations　further　comfirm　that　the　expanded　interlayer　distance　and　C,N-codoping　of　MoS2　nanosheets　promote　the　superior　Na+　intercalation/deintercalation　kinetics.　In　turn,　the　resulted　pseudocapacitance-dominated　electrochemical　behavior　also　enables　the　superior　rate　capability.