The invention discloses a method for preparing a 
cathode material of a 
sodium-
ion battery, namely 
sodium vanadium fluorophosphates. The method comprises the following steps: using a 
vanadium source, a 
phosphorus source and a 
carbon source as main synthetic raw materials; dissolving into deionized water according to the 
molar ratio 1:1:1.2 of 
vanadium: 
phosphorus: carbon, heating in water bath, and continuously stirring to obtain light green pulp; after 
vacuum drying, 
grinding, then transferring into a 
tube furnace, preburning in an 
inert atmosphere at a certain temperature 
rise rate, cooling and then taking out to obtain black VPO4 / C precursor 
powder; mixing the VPO4 / C with NaF according to a stoichiometric ratio, ball-milling for 3 hours, sending into the 
tube furnace, then 
roasting in the 
inert atmosphere at the certain temperature 
rise rate, and cooling along with the furnace to obtain a positive active material NaVPO4F / C. According to the invention, cheap and easily-obtained pentavalent 
vanadium oxide or trivalent 
vanadium oxide is used as the main raw materials to prepare the 
sodium vanadium fluorophosphates 
cathode material through a 
sol gel activated auxiliary two-step high-temperature 
solid phase method, and the sodium vanadium fluorophosphates 
cathode material has the advantages of good stability, uniform particle size and good electrochemical performance. Meanwhile, the method has the advantages of simple synthesis process, short period and low cost and is convenient for large-scale production.