The invention discloses a method for preparing ethylene glycol and 1,2-propylene glycol. In the method, fiber is placed into water to react under the action of a catalyst at the temperature of 200-250 DEG C to obtain the ethylene glycol and the 1,2-propylene glycol. In the method, the fiber is hydrolyzed in hot water; on one hand, the WO3 catalyst, the load WO3 catalyst and the Ru/C catalyst are led into for providing acidity for promoting the acid hydrolysis of the fiber, on the other hand, the intermediate products in the hydrolysis can be inverted into low-carbon matters, and hydrogenationis carried out, so as to obtain the ethylene glycol and the 1,2-propylene glycol. The method has simple process, quick reaction, high efficiency and less energy and is easy for industrialization; no liquid acid is added, and no waste acid is discharged, therefore, the method is environmentally friendly. The method has low requirement on equipment, can not cause the corrosion of the equipment and has small investment; moreover, the inversion rate of the fiber is 100% high, the yield of the ethylene glycol can reach 35%, and the yield of the 1,2-propylene glycol can reach 31%; therefore, the method has significant application value.