Monolayer molybdenum disulfide (MoS₂) was prepared on the SiO₂/Si substrate by Chemical Vapor Deposition (CVD) method, and then treated with sulfur vapor at 300℃ after the monolayer MoS2 transferred to desired substrate by polymethyl methacrylate. The morphology and photoluminescence properties of the samples were characterized by Atomic Force Microscopy (AFM), vacuum fluorescence detection and Raman spectroscopy. The results show that the photoluminescence intensity of the transferred monolayer MoS₂ after sulfur vapor treatment is about 5 times higher than that of the untreated monolayer MoS₂ prepared by CVD. This photoluminescence enhancement effect is due to that part of the sulfur vacancies of the monolayer MoS₂ are filled by the sulfur atom nanoclusters during the sulfur vapor treatment, thereby improving the photoluminescence efficiency. In addition, similar photoluminescence enhancement is observed after sulfur treatment were observed in the monolayer MoS₂ transferred to SiO₂/Si substrate, quartz, alumina, and magnesium fluoride substrates, respectively.