Converting the low-density solar energy into the high-density chemical energy or realizing the direct degradation of organic pollutants by photocatalytic technology is one of the important ways to solve the problem of energy shortage and environmental pollution. Carbon nitride is a polymeric semiconductor photocatalyst that shows important applications in water splitting, pollutant degradation, CO2 reduction and selective organic synthesis. Supramolecular self-assembly of precursors is one of the important synthetic methods of highly-effective nanostructured carbon nitride photocatalyst. Carbon nitride nanomaterials can be prepared by thermal polymerization of the ordered supramolecular aggregation formed by hydrogen bond interaction between the precursors of melamine and triazine derivative. By controlling the reaction parameters and conditions of self-assembly process, the composition, morphology, band structure, optical property, and electron-hole separation efficiency of carbon nitride can be effectively tailored, thus improving the photocatalytic activity of carbon nitride. Herein, the latest research progress concerning the supramolecular self-assembly synthesis of carbon nitride photocatalysts is reviewed. The work of nanostructured carbon nitride photocatalyst is summarized, including copolymerization modified carbon nitride, nonmetal doped carbon nitride, metal doped carbon nitride, metal oxide and carbon nitride composite, carbon nitride based heterojunction, and highly crystalline carbon nitride photocatalyst. The effect of supramolecular self-assembly method on the composition, structure, and photocatalytic activity of the carbon nitride is also illustrated. The future development direction of this field is indicated.