The invention relates to a synthesis method of benzo[d][1,2,3] thiadiazole-7-formic acid trifluoroacetate. The synthesis method comprises the following main steps of: performing esterification on m-aminobenzoic acid serving as an initiative raw material and methanol so as to obtain m-aminobenzoic acid methyl ester; in the presence of a surfactant, reacting the m-aminobenzoic acid methyl ester andthiocyanate so as to obtain N-(3-carbomethoxy phenyl)-thiourea; adding bromine into the N-(3-carbomethoxy phenyl)-thiourea in chlorobenzene or glacial acetic acid to perform a cyclization reaction soas to obtain 2-amino-7-carbomethoxy benzothiazole; performing heating and loop opening on the 2-amino-7-carbomethoxy benzothiazole in aqueous solution of KOH and performing diazotization and loop closing under an acid condition so as to obtain 7-carboxylic acid-[1,2,3] diazosulfide; and in the presence of oxalyl chloride, performing an esterification reaction on the 7-carboxylic acid-[1,2,3] diazosulfide and trifluoroethanol so as to obtain a target product. Compared with the prior art, the method increases the yield of the benzo[d][1,2,3] thiadiazole-7-formic acid trifluoroacetate.