Abstract: With the gradual improvement of water environment quality requirements in China, more stringent wastewater discharge standards have been imposed on textile printing and dyeing enterprises. Ozonization has been widely used for advanced treatment of textile printing and dyeing wastewater, but has technical defects of low utilization efficiency of ozone and incomplete oxidation. A ultrasonic-assisted heterogeneous catalytic ozonation system was constructed by integrating the self-made ceramsite catalyst and ultrasound, and was used for enhancing the treatment of dyeing and printing effluent. The ceramsite catalyst was characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The effects of ceramsite catalytic dosage and ultrasonic frequency on COD_Cr removal efficiency of dyeing and printing effluent in heterogeneous catalytic oxidation system were studied. The reaction by-products of different organic pollutants treated by the advanced oxidation process were analyzed by three-dimensional fluorescence spectrum and GC/MS. The results showed that ceramsite catalysts had a rough surface with crystal sizes ranging from 36 nm to 50 nm. The COD_Cr removal efficiency of the dyeing and printing effluent increased by 10%-15% after adding ceramsite catalysts into the ozonation system. Moreover, the COD_Cr removal efficiency in the ceramsite catalytic ozonation system was further improved by introduction of ultrasound and the ρ(COD_Cr) of the dyeing and printing effluent could meet the V class of National Environmental Quality Standard for Surface Water (GB 3838-2002). The introduction of ceramsite catalyst and ultrasound can enhance oxidation and decomposition of aromatic proteins and soluble metabolite of microorganism, and effectively destroy organic matters such as long-chain alkanes, cyclic alkanes, complex benzene series, etc., thereby realizing further degradation of ρ(COD_Cr) in dyeing and printing effluent. The introduction of ceramsite catalyst and ultrasonic wave is demonstrated to be an environmentally friendly approach for improving the mineralization efficiency of the dyeing and printing tail water in the heterogeneous catalytic ozonation system, which can provide a useful reference for advanced treatment of textile printing and dyeing wastewater.