Graphitic carbon nitride (g-C3N4) has received much attention in recent years due to its unique optical and electrochemical properties. In this review, preparation, properties and some applications of g-C3N4 in energy storage were summarized. In order to improve surface area of g-C3N4, hard and soft template, template-free and exfoliation methods were usually used. The properties of g-C3N4 including stability, optical, photoelectrochemical and electrochemical properties were introduced. Some applications in photocatalysis, electrocatalysis and Li-based batteries were also analyzed. Finally, the outlook of g-C3N4 was also provided.