The invention provides a method for recycling furan ammonium salt from furan ammonium salt waste liquid. The method comprises the following step: reacting by virtue of furan ammonium salt waste slag liquid in the presence of a solvent and a catalyst, wherein the catalyst is selected from one or more of metal chlorate, metal sulfate, metal nitrate, hydrogen phosphate salt, metal oxide, inorganic acid, organic acid and inorganic base, and metal is selected from one or more of sodium, potassium, calcium, magnesium, aluminum, zinc, iron and cobalt, and the reaction temperature is 50-150 DEG C. According to the method, (Z)-formula furan ammonium salt is directly converted from (E)-formula furan ammonium salt through a one-step method by utilizing the furan ammonium salt waste slag liquid at a specific temperature in a special catalyst system in the presence of the solvent, and finally a thermodynamically stable furan ammonium salt product is obtained. The method includes simple steps and is economic, environmentally friendly and suitable for industrial production, the recycling yield of furan ammonium salt is effectively increased, and meanwhile, the environmental protection pressure of the furan ammonium salt waste liquid is decreased.