Plastic wastes threaten the environment security. Degradable materials were considered as the most promising way to solve the problem of plastic pollution. In this work, the cationic dyeable polyester modified with photocatalyst g-C₃N₄/TiO₂ was synthesized by centrifugal electrospinning, which had a photodegradable function under solar illumination. The result indicated that cationic dyeable polyester modified with 5% g-C₃N₄/TiO₂ composite had excellent self-degradation ability in water environment under solar illumination. After 400 h illumination, the polyester matrix could be almost completely degraded. In addition, degradation products and degradation pathway were analyzed by ultra-high-performance liquid chromatography-mass spectrometry. The chain scission of polyester macromolecule led to the generation of formic acid, sodium sulfate, and short chain substances, and then they were degraded into CO₂ and H₂O. The degradation of the macromolecular chain was from large to small, from small to without. The design of the degradable polyester material was conducive to reducing the generation of polyester micro plastic pollutants.