NOVELTY - Synthesizing gastrodin, comprises (i) adding perchloric acid, acetylating anhydrous glucose, detecting the reaction endpoint, and brominating hemiacetal hydroxy group of peracetyl glucose; (ii) adding e.g. chloroform and water, dissolving monobromo tetraacetyl glucose solution, monitoring the reaction endpoint by TLC to obtain condensed compound, and re-crystallizing; (iii) pressurizing, hydrogenating, and reacting; (iv) hydrogenating, filtering, removing the protective group, reacting, and carrying out vacuum drying, to obtain gastrodin; and (v) re-crystallizing to obtain pure gastrodin.    USE - The method is useful for synthesizing gastrodin.    ADVANTAGE - The method is economical, and environmental-friendly; has simple operation procedure; and produces high quality product. The gastrodin meets the medicinal requirements, and is rich in raw materials.    DETAILED DESCRIPTION - Synthesizing gastrodin, comprises: (i) adding perchloric acid as a catalyst, acetylating anhydrous glucose by adding acetic anhydride to produce peracetyl glucose, and controlling the temperature at 30-35 degrees C, detecting the reaction end point by thin-layer chromatography (TLC), completing acetylation, passing hydrogen bromide gas, controlling the temperature at 25-30 degrees C, and brominating hemiacetal hydroxy group of peracetyl glucose to produce monobromo tetraacetyl glucose, where the molar ratio of anhydrous glucose to acetic anhydride to perchloric acid to hydrogen bromide is 1:7.5:0.04:0.76; (ii) adding a two-phase system containing chloroform and water in the volume ratio of 1:1, adding tetra-butyl ammonia bromide as a catalyst, carbonate and p-hydroxybenzaldehyde to the two-phase system, controlling the temperature at 40-60 degrees C, then dissolving monobromo tetraacetyl glucose solution by adding chloroform dropwise, monitoring the end point of the reaction by TLC to obtain a condensed compound 4-formylphenyl-2',3',4',6'-tetraacetyl- beta -D-glucopyranose, and re-crystallizing the condensed compound by 95% ethanol, where the molar ratio of monobromo tetraacetyl glucose to p-hydroxy benzaldehyde to carbonate to tetra-butyl ammonia bromide is 1:0.9-1.2:1-1.2:0.3; (iii) adding the condensed compound to a hydrogen absorption solvent, then adding Raney nickel (RTM: Nickel-aluminum alloy catalyst) or palladium carbon, passing hydrogen gas, pressurizing the material at 0.5 MPa, hydrogenating the material, controlling the temperature at 30-40 degrees C, reacting for 6 hours, and controlling the endpoint of the reaction by TLC detection, where the weight ratio of the Raney nickel (RTM: Nickel-aluminum alloy catalyst) or palladium carbon to the condensed compound is 0.15-0.3:1, the volume/weight ratio of the hydrogen absorption solvent to the condensed compound is 5-10:1; (iv) hydrogenating, filtering, adding sodium alkoxide or ammonia to the filtrate, removing the protective group, reacting for 3-4 hours at 18-25 degrees C, detecting by TLC until the reaction is completed, carrying out vacuum drying, and concentrating the filtrate to obtain gastrodin, where the mass ratio of the sodium alkoxide to 4-formylphenyl-2',3',4',6'-tetraacetyl- beta -D-glucopyranose is 1-3:100, and the mass ratio of ammonia to 4-formylphenyl-2',3',4',6'-tetraacetyl- beta -D-glucopyranose is 2-5:100; and (v) re-crystallizing gastrodin by taking alcohol or a mixed solvent of alcohol and ester or a mixed solvent of alcohol and ketone as a re-crystallizing solvent, to obtain pure gastrodin, where the volume/weight ratio of the re-crystallizing solvent to gastrodin is 4-7:1, the carbonate is sodium carbonate, potassium carbonate or sodium bicarbonate, the alcohol is methanol, ethanol, propanol or isopropanol, the mixed solvent of alcohol and ester is a mixed solvent of methanol and ethyl acetate, a mixed solvent of methanol and butyl acetate, a mixed solvent of ethanol and ethyl acetate, or a mixed solvent of ethanol and butyl acetate, and the mixed solvent of alcohol and ketone is a mixed solvent of methanol and acetone, a mixed solvent of methanol and butanone, a mixed solvent of ethanol and acetone, or a mixed solvent of ethanol and butanone, the Raney nickel (RTM: Nickel-aluminum alloy catalyst) includes types of W-1 to W-3, the palladium carbon (0.5-10%) is sodium alkoxide is sodium methoxide or sodium ethoxide, ammonia is ammonia gas or liquid ammonia, and hydrogen absorption solvent is anhydrous ethanol.