The present invention discloses a method for synthesizing salazosulfapyridine. The synthetic method comprises: step 1, conducting a diazotization reaction on pyridazol using a pipe reactor under the action of hydrochloric acid and isoamyl nitrite in a THF solvent to obtain diazonium salt; and step 2, conducting a coupling reaction on the diazonium salt and salicylic acid in a sodium hydroxide aqueous solution. In the synthetic method provided by the present invention, pyridazol is used as the raw material, and salazosulfapyridine is obtained through the diazotization reaction and the coupling reaction successively, . The diazotization reaction and the coupling reaction have a relatively high conversion rate and relatively few side reactions, thereby improving the product purity and ensuring the yield. In addition, pyridazol is easily available in source, so that the production cost is lowered, and the method has relatively huge industrial production value.