Abstract: o-nitrophenylacetic acid was synthesized by C2H5ONa-catalyzed condensation of o-nitrotoluene with diethyl oxalate and subsequently by hydrolysis，oxidation with H2O2 and acidation with HCl. The yield was about 62％. It was further converted to o-halophenylacetic acid by FeO(OH)-catalyzed reduction with hydrazine hydrate in 20% NaOH aqueous solution，diazonation and substitution with haloatoms. The yield was 65％～73％. The overall yield was about 40％～45％.