Photocatalytic reduction of carbon dioxide is a technology that effectively utilizes CO 2 and solar energy. Sodium niobate (NaNbO 3 ) has received much attention in the field of photocatalysis due to its excellent photocatalytic properties. However, the application of NaNbO 3 in the field of photocatalysis is still limited by poor reaction to visible light and easy recombination of photo-generated carriers. Heterojunction with g-C 3 N 4 to construct core-shell structure can effectively improve the above problems. Combining the two can design a core-shell composite material that is beneficial for photocatalytic reduction of CO 2 . Herein, we prepared a core-shell heterojunction g-C 3 N 4 /NaNbO 3 by uniformly impregnating urea on the surface of NaNbO 3 chromium nanofibers with NaNbO 3 nanofibers prepared by electrospinning as a catalyst carrier, and urea as a precursor of g-C 3 N 4 . The core-shell structure of g-C 3 N 4 /NaNbO 3 was verified by a series of characterization methods such as XPS, XRD, and TEM. It was found that under the same conditions, the methanol yield of core-shell g-C 3 N 4 /NaNbO 3 was 12.86 μ mol·g -1 ·h -1 , which is twice that of pure NaNbO 3 (6.67 μ mol·g -1 ·h -1 ). This article highlights an impregnation method to build core-shell structures for improved photocatalytic reduction of CO 2 .