The CoN which with excellent performance was introduced into Mn0.2Cd0.8S through simple electrostatic self-assembly for the first time, then the composite photocatalyst with low cost and high catalytic activity was prepared. The introduction of CoN improves the absorption intensity of catalyst to visible light. CoN accepts photo-induced electrons from Mn0.2Cd0.8S as an excellent electron acceptor in the form of active sites due to its suitable conduction band position and good conductivity. The surface interaction of composite photocatalyst formed by electrostatic self-assembly is strong, which is conducive to the directional transfer of photogenic carriers from Mn0.2Cd0.8S to CoN, greatly inhibits the recombination of photogenic carriers and improves the separation and the transfer rate of photogenic carriers. The introduction of CoN greatly improved the hydrogen production rate of photocatalyst up to 14.612 mmol g(-1) h(-1), it was 17.3 times that of pure MCS. This work provides inspiration for transition metal nitrides as cocatalysts in the sphere of photocatalytic splitting of water for hydrogen production. (C) 2020 Elsevier Inc. All rights reserved.