The invention discloses a synthesis method of 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol. The method comprises the following reaction steps of: 1, reacting 2,3,5,6-tetrafluorobenzyl alcohol with hydrogen halide in a solvent for 2-20h at 40-120 DEG C to obtain 3-halomethyl-1,2,4,5-tetrafluorobenzene; 2, reacting the 3-halomethyl-1,2,4,5-tetrafluorobenzene in methanol for 1-20h at 0-65 DEG C under the action of an inorganic alkali to obtain 3-methoxymethyl-1,2,4,5-tetrafluorobenzene; 3, dissolving the 3-methoxymethyl-1,2,4,5-tetrafluorobenzene into an inert solvent, dripping an organic lithium reagent at 0-78 DEG C to react for 0.5-5h, inputting formaldehyde gas into the reaction system to continuously react for 0.5-5h, and carrying out the quenching reaction by a protonic solvent to obtain the 4-methoxymethyl-2,3,5,6-tetrafluorobenzyl alcohol. The synthesis method provided by the invention has the advantages of good reaction selectivity, cheap and available reagents, and high reaction yield and high purity of the product.