Photocatalytically converting CO2 into valuable energy fuels such as CO, CH4, HCOOH and CH3OH with photocatlayts and sunlight is a dream technology to realize artificial photosynthesis. The utilization of g-C3N4 for CO2 photocatalytic reduction deserves a highlight not only for the different reaction routes that may take place on this distinct material, but also because of the great potential of this relatively cheap catalyst. In this article, the recent advances on g-C3N4-based composites for CO2 photocatalytic reduction are critically reviewed. The review starts with a brief introduction of the key steps for CO2 photocatalytic reduction as well as the basic properties of g-C3N4. Then g-C3N4-based materials for CO2 adsorption and activation are discussed to provide a better understanding of the important active sites on g-C3N4 for CO2 adsorption/activation, which are very different from many metal oxide photocatalysts. In the main section, g-C3N4 and three major types of g-C(3)N(4-)based composites that have been studied for CO2 photoreduction are reviewed. Finally, recommendations on future studies to achieve a higher efficiency in CO2 photocataltic reduction with g-C3N4-based materials are given.