TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The strong alkali is organic amine alkaline metal, organic amine alkaline earth metal, alkoxy alkaline metal, alkoxy alkaline earth metal or alkaline metal hydride. The metal boron hydride is sodium boron hydride, potassium boron hydride or lithium boron hydride.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The substitution reaction is performed by utilizing solvent that is 5-16C alkane, 4-10C ether or simple aromatic hydrocarbon. The catalyst-I is boron trifluoride or aluminum chloride. The reduction reaction is performed by utilizing solvent that is ether and/or alcohol. The catalyst-II is a lewis acid catalyst, where the lewis acid catalyst is aluminum chloride, calcium chloride, magnesium chloride, zinc chloride, zinc trifluoroacetic acid, titanium tetrachloride or titanium ethoxide. The acid catalyst-III that is utilized in the in the cyclization reaction in the method for synthesizing 3-hydroxymethyl tetrahydrofuran is sulfuric acid, acid potassium sulphate, acid sodium sulphate, hydrochloric acid, phosphoric acid, poly-phosphoric acid, formic acid, p-toluenesulfonic acid, methanesulfonic acid or high polymer sulfoacid resin. Preferred Composition: The molar ratio between gamma -butyrolactone and substituted propanone compound of formula (I) or formaldehyde is 1:1-1:2.0. The molar ratio between the alpha -substitutive gamma -butyrolactone and the metal boron hydride is 1:1.5-3.0. Preferred Process: The reduction reaction is performed using alpha -substitutive gamma -butyrolactone to obtain 2-hydroxymethyl-1,4-butanediol in the presence of a metal catalyst-II, the 2-hydroxymethyl-1,4-butanediol is reacted with acid for neutralization, filtered and concentrated. The concentrated solution is subjected to cyclization in the presence of catalyst-III to generate the 3-hydroxymethyl tetrahydrofuran. The reduction reaction is performed below -10-100 degrees C, and reaction time is 0.5-10 hours. The method for synthesizing 3-hydroxymethyl tetrahydrofuran further comprises cyclization reaction, which is performed at 30-200 degrees C and the reaction time is 0.5-24 hours.