The invention discloses a method for synthesizing pyridinium hydroxy propyl sulfobetaine. The method comprises the following steps of: dissolving pyrosulfite or bisulfite of alkali metal into water, and performing a ring-opening addition reaction of the obtained solution and epichlorohydrin to obtain a ring-opening product with the following chemical formula in the presence of sulfite and a phasetransfer catalyst, wherein M is alkali metal in the formula; and dissolving the ring-opening product into water, reacting the obtained solution and pyridine, and purifying to obtain the pyridinium hydroxy propyl sulfobetaine (PPS-OH) after the reaction is finished. By the method for synthesizing the PPS-OH, the yield is high, byproducts are avoided, a product does not contain free pyridine, and the electroplating effect is better. Meanwhile, the method is pollution-free, and is more favorable for environmental protection because water is taken as a solvent. Moreover, the catalyst is added, sothat catalytic reaction effect is better, reaction speed is higher, conditions are easier to control, and the method is applicable to industrialized production. The aeration of inert gas into the reaction can also reduce the polymerization of free radicals of the epichlorohydrin caused by the existence of oxygen, so that the yield is further improved.