Abstract: The high defect density, low specific surface area and high band gap energy of pure g-C₃N₄ seriously limit its photocatalytic efficiency, the photocatalytic activity can be improved by doping the precursor of the catalyst. CDs modified lamellar g-C₃N₄ was prepared by heat treatment of CDs modified dicyandiamide. The composition of the materials was confirmed by XRD, FT-IR, UV-Vis, SEM and TEM, and the photocatalytic activity was systematically tested. The results show that the prepared 4-CDs-CN has stronger degradation effect on TC, and the degradation rate reaches 80.7% within 1 hour, which is 59.8% higher than that of pure g-C₃N₄ (50.5%). The loading of CDs promotes the separation of photogenerated carriers and enhanced the photocatalytic activity. The aerogel provides a new way for the preparation of metal-free carbon-based semiconductor photocatalytic materials.