Na3V2(PO4)(3) (NVP) is considered as a promising cathode material in Sodium-ion batteries (SIBs). However, the intrinsically poor electronic conductivity greatly limits its electrochemical performances and practical applications. Herein, a solid-state annealing process using a facile surfactant-assisted method has been developed to fabricate a three-dimensional (3D) Na3V2(PO4)(3)/ C (NVP/ C) composite with hierarchical nanoflake-assembled structure. Sodium oleate functions both as sodium and carbon sources. Moreover, it dictates the preferential growth of nanocrystal as a surfactant. This flaky structure coated by carbon can ensure the excellent electrochemical performances of the NVP/C composite, such as high reversible capacity (103.4 mA h g(-1) at 1 degrees C), excellent rate capability (68.3 mA h g(-1) at a rate up to 20 degrees C) and good cycling stability (a capacity retention of 78.2% after 2000 cycles at 10 C).