NOVELTY - Preparing liranaftate comprises (i) adding 2,6-dichloropyridine and sodium methoxide into a reaction vessel, heating and carrying out reflux reaction to obtain 6-methoxy-2-chloropyridine; (ii) adding 6-methoxy-2-chloropyridine, cuprous chloride and aqueous methylamine solution into an autoclave, and reacting for 7 hours to obtain 6-methoxy-2-aminopyridine; (iii) synthesizing 5,6,7,8-tetrahydro-2-naphthyloxy thionyl chloride; and (iv) reacting 5,6,7,8-tetrahydro-2-naphthyloxy thionyl chloride with ionic liquid, 6-methoxy-2-aminopyridine and potassium carbonate.    USE - The method is useful for preparing liranaftate (claimed).    ADVANTAGE - The method has mild reaction conditions, simple operation, is easy to separate and purify, produces high yield, high purity and residual quantity of related substances, and is environmentally friendly.    DETAILED DESCRIPTION - Preparing liranaftate comprises (i) adding 2,6-dichloropyridine and sodium methoxide of molar ratio 1:2 into a reaction vessel, heating and carrying out reflux reaction for 4-5 hours, detecting completion of the reaction by thin layer chromatography, concentrating with methanol, adding water, extracting with ethyl acetate, combining organic phases, cleaning with saturated brine, drying, filtering and concentrating the filtrate to obtain colorless oily substance 6-methoxy-2-chloropyridine; (ii) adding 6-methoxy-2-chloropyridine, cuprous chloride and aqueous methylamine solution into an autoclave, sealing, heating to 120 degrees C, reacting for 7 hours, adding ethyl acetate, extracting, combining organic phases, washing with saturated brine, drying, and concentrating the filtrate to obtain brown oily substance 6-methoxy-2-aminopyridine; (iii) mixing ethyl acetate, thiophosgene and 5,6,7,8-tetrahydro-2-naphthol, cooling in ice-salt bath at 0 degrees C, dropping potassium carbonate solution, stirring and reacting, detecting completion of the reaction by thin layer chromatography, adding water, extracting with ethyl acetate, combining organic phases, cleaning with saturated brine, drying, filtering and concentrating the filtrate to obtain yellow oily 5,6,7,8-tetrahydro-2-naphthyloxy thionyl chloride; and (iv) mixing ionic liquid, 6-methoxy-2-aminopyridine and potassium carbonate, cooling with ice water, dropping 5,6,7,8-tetrahydro-2-naphthyloxy thionyl chloride, reacting for 4 hours, stirring adding water, stirring continuously for 20 minutes, filtering, washing with deionized water to obtain crude product, and recrystallizing the crude product with acetone to obtain white crystalline powder liranaftate, where the ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate, N-ethylpyridinium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-hydroxyethyl-2,3-dimethylimidazolium chloride, 1-propyl-3-nitrile-methylimidazole chloride, 1-carboxymethyl-ethyl-3-methylimidazolium chloride, N-methyl pyrrolidonium hydrosulfate or bisazaindolyloxindole.