The invention relates to a preparation method of a pyridoxal phosphate intermediate. The preparation method comprises the following steps: (1) adding a TEMPO type catalyst, an NO compound, a Br-containing compound and an oxidizing agent or a TEMPO type catalyst, sodium hydrogen carbonate, the Br-containing compound and the oxidizing agent into a compound III or hydrochloride thereof which is taken as a starting raw material in water for carrying out a TEMPO oxidation reaction so as to obtain a compound II, wherein the TEMPO type catalysts are TEMPO or derivatives thereof and TEMPO with fixed forms; (2) after the reaction of the step (1) is finished, adding a compound IV, stirring to produce a great deal of yellow solid, filtering, and drying to obtain a compound I. The preparation route of the preparation method is described in the description. The preparation method provided by the invention has the advantages that the preparation method is simple and convenient to operate, mild, efficient, environment-friendly, easy in realization of industrial production and high in product yield.