The photocatalysis technology becomes more and more mature. As a non?metallic visible light responsive catalyst, carbon nitride (g?C₃N₄) has attracted wide attention in the field of solar energy conversion and environmental protection due to its adjustable band gap structure, high physicochemical stability and environmental friendliness. It has become a new research hotspot. However, g?C₃N₄ also has some defects, such as small specific surface area, recombination of photogenerated electron and holes, and low utilization rate of light energy,which limit the application of g?C₃N₄ in practice.Therefore,the review focus on the development and research results of g?C₃N₄,and summarizes g?C₃N₄ from the aspects of development process,synthesis method, performance application,modification and optimization,and predicts how to further improve the performance of g?C₃N₄ to cope with the future development of the world.