Abstract In this paper, ultra‐thin g‐C 3 N 4 nanosheets were prepared by improved ultrasonic stripping method for the first time. Then, g‐C 3 N 4 nanosheets were pretreated into Bi + /g‐C 3 N 4 nanosheets by electrostatic adsorption principle, and a new type of Cl‐Bi 2 WO 6 /g‐C 3 N 4 heterostructure photocatalyst was prepared by using Bi + /g‐C 3 N 4 nanosheets as the substrate. The degradation of RhB under photocatalysis was studied with the compound amount of g‐C 3 N 4 and the amount of catalyst by using x‐ray diffraction (XRD), a scanning electron microscope (SEM), high‐resolution transmission electron microscopy (HRTEM), x‐ray photoelectron spectroscopy (XPS), Brunauer Emmett‐Teller (BET), and ultraviolet visible diffuse (UV‐vis DRS) methods on the structure, morphology, and optical characterization charge transfer characteristics, etc. The results of the degradation experiment show that the compound appropriate amount of g‐C 3 N 4 can significantly improve the activity of the photocatalyst. At the same time, different amounts of Cl‐Bi 2 WO 6 /g‐C 3 N 4 composite photocatalyst have a significant effect on the degradation performance, and the photocatalytic activity is the best when the input is 2 g/L. Combined with active species capture experiments, a possible degradation mechanism of Cl‐Bi 2 WO 6 /g‐C 3 N 4 Z‐type heterostructure photocatalyst was proposed.