In this study, we present the growth of monolayer MoS2(molybdenum disulfide) film. Mo (molybdenum) film was formed on a sapphire substrate through e-beam evaporation, and triangular MoS2film was grown by direct sulfurization. First, the growth of MoS2was observed under an optical microscope. The number of MoS2layers was analyzed by Raman spectrum, atomic force microscope (AFM), and photoluminescence spectroscopy (PL) measurement. Different sapphire substrate regions have different growth conditions of MoS2. The growth of MoS2is optimized by controlling the amount and location of precursors, adjusting the appropriate growing temperature and time, and establishing proper ventilation. Experimental results show the successful growth of a large-area single-layer MoS2on a sapphire substrate through direct sulfurization under a suitable environment. The thickness of the MoS2film determined by AFM measurement is about 0.73 nm. The peak difference between the Raman measurement shift of 386 and 405 cm−1is 19.1 cm−1, and the peak of PL measurement is about 677 nm, which is converted into energy of 1.83 eV, which is the size of the direct energy gap of the MoS2thin film. The results verify the distribution of the number of grown layers. Based on the observation of the optical microscope (OM) images, MoS2continuously grows from a single layer of discretely distributed triangular single-crystal grains into a single-layer large-area MoS2film. This work provides a reference for growing MoS2in a large area. We expect to apply this structure to various heterojunctions, sensors, solar cells, and thin-film transistors.