The invention provides a synthetic method for 2-picolinic acid, belonging to the field of organic chemical synthesis. The synthetic method comprises the following steps: adding acetonitrile and a catalyst composed of cobaltocene, manganese acetate and cobalt acetate into a reaction vessel, introducing acetylene at room temperature and carrying out stirring and heating for a reaction so as to prepare 2-methylpyridine; heating 2-methylpyridine with a heating bed so as to turn 2-methylpyridine into steam, then mixing the 2-methylpyridine steam with ammonia gas, water vapor and air and carrying out catalytic oxidation via a catalyst layer so as to prepare 2-pyridinecarbonitrile; and adding 2-pyridinecarbonitrile into a sodium hydroxide solution, successively carrying out heating, stirring reaction, cooling to room temperature and pumping filtration, washing a filter cake and carrying out drying and crystallization so as to obtain 2-picolinic acid. The synthetic method provided by the invention has the advantages of high yield, simple production process, easiness in product separation and low production of waste gas, waste water and industrial residues.