The invention discloses a method for synthesizing a 4-dihydroxyborane-2-fluorophenylalanine, wherein the method comprises the following steps of taking p-iodotoluene as a raw material, carrying out nitratlon reaction and bromination reaction in sequence on the raw material to obtain p-iodo-o-nitrobenzyl bromine, firstly substituting the p-iodo-o-nitrobenzyl bromine with diethyl sodium acetamidomalonate to obtain diethyl 2-acetamido-2-(4-iodo-2-nitrobenzyl) malonate, and then reacting with ammonium tetrabutyl fluoride to obtain fluorinated diethyl 2-acetamido-2-(4-iodo-2-fluorobenzyl) malonate, carrying out Suzuki coupling reaction on the obtained fluorinated product and bisdiboron under an inert atmosphere, hydrolyzing the obtained diethyl 2-acetamido-2-(4-valerylboron-2-fluorobenzyl) malonate to obtain the 4-dihydroxyborane-2-fluorophenylalanine. The method provided by the invention is not necessary to use fluorine gas; the method provided by the invention has low requirement to production equipment; the reaction is carried out under common experimental conditions; the method provided by the invention has the advantages of simple synthesis step, high yield, high product purity and easy purification.