The invention belongs to the technical field of preparation of sorbic acid, and particularly relates to a method for preparing sorbic acid through photo-efficient catalytic isomerization, and the method comprises the following steps: (1) putting sorbic acid polyester into a reaction kettle, adding deionized water, turning on a light source, putting a solid base catalyst, stirring and heating to react; (2) after the reaction is finished, filtering while hot to obtain a sorbic acid aqueous solution; (3) cooling, crystallizing, washing and drying to obtain the sorbic acid, wherein the solid basecatalyst is supported anion exchange resin, macroporous anion resin is taken as a carrier, EDTA (Ethylene Diamine Tetraacetic Acid) is taken as a complexing medium, palladium, platinum, zinc or copperions are supported, and the loading capacity is 0.1-1wt%. According to the method, the photocatalysis technology is simple and convenient to operate and environmentally friendly, the adopted supported ion exchange resin is high in alkalinity and short in catalytic reaction time, the production efficiency is improved, meanwhile, the supported metal ions and a light source have a synergistic promotion effect on isomerization, and the amount of byproduct tar can be further reduced.