The invention discloses preparation of rhenium sulfide and a cadmium sulfide/rhenium sulfide composite material. A two-dimensional monolayer rhenium disulfide is grown on a mica sheet substrate through an ordinary pressure chemical vapor deposition method with sulfur powder as a sulfur source and rhenium trioxide as a rhenium source under protection of an inert gas and a water-assisting precondition; by means of a secondary growth method, cadmium sulfide particles are again deposited on the mica sheet substrate with the two-dimensional monolayer rhenium disulfide, and a CdS/ReS2 composite material with the cadmium sulfide particles growing on the surface of the rhenium sulfide is obtained. The preparation of the rhenium sulfide and the cadmium sulfide/ rhenium sulfide composite material have the advantages that the process is simple, low-cost, rapid, highly efficient and controllable, and the high-quality single-layer rhenium sulfide is prepared. The CdS/ReS2 composite material obtained by depositing the cadmium sulfide on the two-dimensional material rhenium sulfide has more excellent photoelectric properties and has a high response rate while being applied to a photoelectric device.