The conversion of CO2 into high value-added carbon-based compounds through photocatalytic reduction technology is considered as one of the more promising strategies to solve the greenhouse effect. And construction of heterojunction photocatalysts can promote the separation of photoelectron-hole pairs, so as to achieve higher activity of photocatalytic CO2 reduction. Hence, [email protected]2/3DCN heterojunction are prepared by calcination method and photoreduction technology. The photocatalytic results revealed that [email protected]2/3DCN show better photocatalytic activity for reducing CO2 into CO and CH4, compared with 3DCN. Especially, [email protected]2/3DCN shows the maximum photocatalytic activity of 4.69 and 3.03 μmol·h−1·g−1 for CO and CH4 under UV light irradiation, respectively, and the reduction activity did not decrease significantly after five cycles. The enhanced photoreduction of CO2 performance can be ascribed to the synergistic effects of the oxygen vacancies in CeO2 for CO2 activation and heterojunction for electron separation. Besides, Pt nanoparticles (NPs) on CeO2/3DCN can further promote the transfer of electrons, resulting in higher photocatalytic activity.