Na3V2(PO4)(3)　is　a　promising　potential　cathode　for　sodium-ion　batteries　owning　to　its　stable　three-dimensional　structure　framework.　However,　from　the　perspective　of　environmental　protection,　the　substitution　of　vanadium　with　low　cost　and　low　toxicity　elements　is　pressing　to　further　boost　its　application　in　large-scale　energy　storage　production.　To　reduce　the　content　of　V　in　Na3V2(PO4)(3)　and　increase　the　transfer　number　of　sodium　ions,　ball-milling　assisted　sol-gel　routine　is　employed　to　prepare　Na4FeV(PO4)(3)@C　sodium-rich　cathode,　which　delivers　an　initial　charge　capacity　high　to　175.6　mAh　g(-1)　with　high　coulombic　efficiency　of　99%　from　1.3　to　4.3　V,　deriving　from　V(II)/V(III),　Fe(II)/Fe(III),　V(III)/V(IV)　and　V(IV)/V(V)　redox　couples.　The　cathode　shows　long-life　span　with　an　excellent　retention　of　96.8%　after　800　cycles　at　5C　from　1.8　to　3.8V.　Solid-state　Na-23　nuclear　magnetic　resonance　reveals　that　the　sodium　ions　at　8-coordinated　Na2　sites　in　Na4FeV(PO4)(3)@C　show　faster　extraction/insertion　dynamics　during　electrochemical　cycling.　X-ray　diffraction　and　time-of-flight　neutron　powder　diffraction　results　demonstrate　that　the　electrochemical　process　undergoes　a　reversible　solid　solution　reaction　with　stable　structure,　resulting　in　fast　rate　performance　and　excellent　cyclic　retention.　The　composition　modulation　of　the　sodium　rich　material　and　the　cycling　mechanisms　obtained　from　this　study　would　contribute　a　great　insight　for　the　sodium　energy　storage　with　improved　performances.