Semiconductor heterojunction photocatalysts have received much concern due to their great application prospect in solar energy utilization and conversion.Rational construction of heterostructure with two or more semiconductor materials can integrate the advantages of multi-components to simultaneously improve the photo-induced charges separation,extend visible light absorption range and retain the high redox ability of photocatalysts.Recently,constructing of g-C3N4-based heterostructure has become a hot focus due to the multiple merits of g-C3N4,such as facile synthesis,high stability,unique optical and electronic characteristics.This review tries to give a comprehensive introduction and provide the possible tendency in design and fabrication of g-C3N4-based heterojunction photocatalysts,especially in rational synthesis of type-ll heterojunction,direct Z-scheme heterojunction,new type of S-scheme het-erojunction,p-n heterojunction and Schottky heterojunction.Furthermore,the special charges transfer mechanisms of g-C3N4-based heterojunctions are discussed and their potential applications in photocat-alytic water splitting,photo-degradation of contaminants and photo-reduction of CO2 into fuels are also summarized.Finally,we attempt to propose some crucial issues based on the current research,which should be further investigated and resolved in this interesting research area.