The Co3O4/CN-x%CeO2 (x = 0, 3, 6) composites for enhanced photocatalytic degradation of formaldehyde (HCHO) performance were prepared by hydrothermal-calcination method. The structure, microstructure and surface functional groups of samples were investigated by using the X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer, and the degradation mechanism of Co3O4/CN-3%CeO2 was also discussed this paper. The results showed that the Co3O4/CN-3%CeO2 sample could degrade 91.5% of HCHO within 9 h which was 190% higher than that of the CN, and maintained excellent performance for 24 h. The sample was in the form of irregular block-based flakes and particles, the specific surface area was 111.92 m2/g which was 2.5 times than that of the CN sample. The sample was composed of CN and Co3O4 phases, existed O–H, N–H, C=O, C–N, Co–O, Ce–O functional group and mesoporous structure with pore size distribution of 2 to 20 nm. [ABSTRACT FROM AUTHOR]