Copper sulfide nanomaterials are characterized by a narrow band gap. Using copper chloride, 1-octadecene and oleylamine as raw materials, copper sulfide nanocrystals are synthesized by high-temperature pyrolysis. The synthesized copper sulfide is characterized and analyzed by XRD, TEM, absorption spectroscopy, infrared spectroscopy and other means. The experimental results prove that the copper sulfide nanocrystals we synthesized are Cu_1.1S, the morphology is particle-like, and the dispersion is uniform. It is used in photocatalysis. It is found that copper sulfide has relatively high photocatalytic activity in the ultraviolet and visible regions. After irradiating with a 35W xenon lamp for 40min, we found that the degradation rate of methylene blue using copper sulfide as a catalyst can reach 97.8%.