Transition metal dichalcogenide (TMDC) monolayers exhibit enhanced electrical and optoelectrical properties, which are promising for next-generation optoelectronic devices. However, large-scale and uniform growth of TMDC monolayers with large grain size is still a considerable challenge. In this work, a simple and effective approach for largescale molybdenum (MoS₂) disulfide monolayers is presented by chemical vapor deposition (CVD) method. It is found that MoS₂ grew from single crystal to thin film with the increasing of oxide precursor proportion. The photodetector of large scale monolayer layer MoS₂ film was fabricated by depositing metal electrodes on the interdigital electrode mask using thermal evaporation coating. Finally, the highly stable and repeatable photoelectric response at different voltages and different laser power conditions was characterized under 405 nm laser excitation, with response time down to the order of milliseconds (ms). In addition, the photodetector achieved a wide spectrum detection range of 405 nm to 830 nm which from visible to near infrared, with optical response (<i>R</i>) up to 291.7 mA/W and optical detection rate (<i>D</i>^*) up to 1.629×10⁹ Jones. Themonolayer MoS₂ thin film photodetector demonstrated here has the advantages of low cost, feasibility of large-scale preparation, and good stability and repeatability in the wide spectrum range from visible to near infrared, which providing the possibilities for the application of electronic and optoelectronic devices in the near future.