NOVELTY - Ethylene glycol and deionized water are mixed, ascorbic acid is added, stirred, and mixed phosphoric acid and ferrous sulfate heptahydrate, to obtain solution. Phosphoric acid and lithium hydroxide are added in mixed solvent, to obtain lithium hydroxide solution. Lithium hydroxide solution is slowly dripped to solution under stirring, ferrous sulfate and ascorbic acid, forming precipitation suspension, and polyethylene glycol is added to suspending liquid. Lithium iron phosphate is transferred to reactor, and filtered, to obtain lithium iron phosphate single-crystal nanorods.    USE - Preparation of lithium iron phosphate single-crystal nanorods (claimed).    ADVANTAGE - The method economically and environmentally-friendly provides lithium iron phosphate single-crystal nanorods having stable quality, high purity, and favorable particle dispersibility and lithium ion diffusion, by simple process. The lithium ion battery has improved electrochemical performance.    DETAILED DESCRIPTION - Ethylene glycol and deionized water in volume ratio of 3:1-1:3, are mixed, to obtain mixed solvent of glycol and water. Ascorbic acid is added to mixed solvent, and stirred, to obtain ascorbic acid solution. Ascorbic acid solution and phosphoric acid are mixed with ferrous sulfate heptahydrate, and fully stirred, to obtain solution containing phosphoric acid, ferrous sulfate and ascorbic acid. Phosphoric acid and lithium hydroxide are added in a mixed solvent, and fully stirring, to obtain lithium hydroxide solution. Lithium hydroxide solution is slowly dripped to solution containing phosphoric acid, ferrous sulfate and ascorbic acid under stirring, ferrous sulfate and ascorbic acid, forming precipitation suspension, and polyethylene glycol is added to the suspending liquid under stirring. 10-100 wt.% Lithium iron phosphate is transferred to the high pressure reactor with volume of 2/3-4/5, stirring for 5 minutes or less, sealed and heat preservation for 160-240 degrees C for 36 hours, cooled to room temperature, and filtered using deionized water, absolute ethyl alcohol or acetone, at 40-100 degrees C, to obtain the lithium iron phosphate single-crystal nanorods. The mol ratio of phosphate and iron is 1:1. The content of ascorbic acid is 10-30 wt.%. The concentration of ferrous sulfate heptahydrate is 0.05-0.5 mol/L. The mol ratio of lithium and phosphate is 3:1. The concentration of lithium hydroxide is 0.15-1.5 mol/L. The lithium iron phosphate nano crystal rods radial size of 50-200 nm, and length of 0.5-10 microns.