With the acceleration of industrialization, energy shortage and environmental pollution are becoming more and more serious. It is urgent to develop green and sustainable new energy. Photocatalytic technology, especially the use of solar energy to convert chemical energy, has attracted much attention due to its environmental friendliness and sustainability. As an excellent photocatalyst, graphitic carbon nitride (g-C₃ N₄ ) has emerged rapidly in the field of photocatalysis due to its low cost, simple preparation and non-toxicity. However, g-C3 N4 has some limitations in practical applications, such as small specific surface area, weak photogenerated carrier transport capacity and narrow visible light response range. To overcome these challenges, researchers have modified g-C₃ N₄ through various strategies to improve its photocatalytic performance. In this paper, the synthesis methods and modification strategies of g-C₃ N₄ are summarized from the structural characteristics of g-C₃ N₄ , and its research focus and application prospect in the field of photocatalysis are prospected