The invention provides a preparation method of a flexible self-supporting Li3VO4 / C 
nanofiber lithium ion battery negative 
electrode material, which comprises the following steps: adding 
lithium nitrate, 
ammonium metavanadate and 
oxalic acid into a proper amount of N, N-
dimethylformamide, and stirring in a water bath at a constant temperature; meanwhile, taking 
polyacrylonitrile to be added into N, N-
dimethylformamide and stirred, then slowly dropping the mixture into the solution, and obtaining a precursor 
fiber membrane through electrostatic 
spinning; and when the 
spinning process is finished, removing the precursor 
fiber membrane from the steel roller, 
drying, and calcining to obtain the flexible Li3VO4 / C 
nanofiber. The flexible self-supporting Li3VO4 / C 
composite nanofibers are prepared by combining the electrostatic 
spinning technology with high-temperature 
solid-phase 
sintering for the first time to serve as the negative 
electrode material of the 
lithium ion battery, the synthesis process method is simple, convenient and easy to operate, a prepared sample does not need an additional binder, a conductive agent and a 
current collector and can be directly 
cut to serve as an 
electrode plate for use, and the material has good mechanical flexibility and shows excellent electrochemical performance.