Abstract: With the wide application of epoxy resin-based carbon fiber composites, the recycling of their waste products had become an important issue for low-carbon development. The resin degradation mechanism of epoxy resin-based carbon fiber composites containing ester bonds and the effect of degradation process on the structure and properties of recycled carbon fibers were studied by GC-MS, FTIR, XPS, SEM and other characterization methods. The results show that the optimal degradation time is 1 h under the conditions of benzyl alcohol dosage of 120 mL, mass ratio W (NaOH)∶W (ZnCl₂)=1∶1 and degradation temperature of 190℃, and the optimal dosages of NaOH and resin are both 1 g. The degradation products are separated by standing stratification, and the content of benzyl alcohol in the supernatant is 99%. The degradation mechanism of the resin is as follows: Firstly, benzyl alcohol is ionized to generate benzyloxy group in an alkaline environment, and the benzyloxy groups attack ester bonds in the resin, and transesterification reaction occures to break the ester bond to achieve degradation. Benzyl alcohol ester and alcohol anion are produced by transesterification reaction. Next, the benzyl alcohol ester undergoes saponification reaction in alkaline environment to regenerate benzyl alcohol. The transesterification reaction and the saponification reaction are repeated until the final degradation is completed. The surface O/C and surface smoothness of the recycled carbon fibers and the original carbon fibers are at the same level, and the strength retention rate of the recycled carbon fibers reaches 97%.