NOVELTY - A recrystallized solid salt functional carbon material is prepared by ultrasonically dispersing carbon precursor suspension liquid in deionized water to obtain 5 g/ml carbon precursor suspension, soaking for 6 hours, filtering, washing, ultrasonically dispersing residue in ethanol to obtain 5 g/ml carbon precursor ethanol dispersion, soaking for 6 hours, washing with deionized water and ethanol, drying under vacuum state for 24 hours to obtain carbon precursor, and weighing carbon precursor:iron salt:cobalt salt with mass ratio of 1:0-4:0-4.    USE - Preparation of recrystallized solid salt functional carbon material for fuel cell cathode catalyst, supercapacitor electrode material, and electric double layer capacitor.    ADVANTAGE - Preparation process is simple and easy and has low cost. Product has high surface area, high mass transfer efficiency, good graphite structure, good conductivity, and excellent electrochemical properties.    DETAILED DESCRIPTION - A recrystallized solid salt functional carbon material is prepared by ultrasonically dispersing carbon precursor suspension liquid in deionized water to obtain 5 g/ml carbon precursor suspension, soaking for 6 hours, filtering, washing, ultrasonically dispersing residue in ethanol to obtain 5 g/ml carbon precursor ethanol dispersion, soaking for 6 hours, washing with deionized water and ethanol, drying under vacuum state for 24 hours to obtain carbon precursor, weighing carbon precursor:iron salt:cobalt salt with mass ratio of 1:0-4:0-4, dissolving 60-250 g soluble salt crystal in 120-250 ml deionized water at 60-90 degrees C to obtain soluble salt supersaturated solution, dispersing carbon precursor in 5-15 ml deionized water, ultrasonically mixing for 1-3 hours to obtain 0.2-5 g/ml carbon precursor suspension, adding iron salt and cobalt salt in carbon precursor suspension, stirring for 12-36 hours to adsorb, adding 5-25 ml soluble salt supersaturated solution, stirring for 2-4 hours, evaporating solvent at 60-95 degrees C, slowly dropping 110-210 ml soluble salt supersaturated solution, crystallizing, adding water, evaporating to obtain 5-15 ml soluble salt supersaturated solution, placing in vacuum oven at - 0.05 MPa to - 0.1 MPa, crystallizing at 30-70 degrees C for 12-24 hours to obtain soluble salt crystal encapsulated carbon precursor, dehydrating at 110-160 degrees C for 1-5 hours under protection of nitrogen or argon atmosphere, performing pyrolysis at 800-1100 degrees C, cooling at room temperature to obtain soluble salt crystals encapsulated carbonized carbon precursor, dissolving in 0.1-1 mol/L acidic aqueous solution, stirring at 60-90 degrees C for 2-5 hours, filtering under vacuum state, washing with deionized water, washing with absolute ethanol, and drying at 60 degrees C for 24 hours to obtain functional carbon material in which iron salt is ferric chloride, ferric sulfate, ferric nitrate, or iron acetate, cobalt salt is cobalt chloride, cobalt sulfate, or cobalt nitrate and cobalt acetate, and soluble salt is potassium chloride, barium chloride, sodium chloride, calcium chloride, sodium carbonate, sodium sulfate, or potassium bromide.    DESCRIPTION OF DRAWING(S) - The drawing shows a test curve of cathodic oxygen reduction catalyst proton exchange membrane hydrogen fuel cell. (Drawing includes non-English language text).