Developing flexible photodetectors is crucial for both military and civil fields. Large-area MoS2 films from several to dozens of layers are controllably synthesized via a facile atmospheric-pressure sulfurization route of predeposited Mo films and transferred onto other substrates (e.g. SiO2/Si wafers, quartz slides, polymers). The flexible photodetectors were fabricated by transferring as-synthesized MoS2 films onto interdigital electrodes patted on polyethylene terephthalate (PET) substrates. No additional complex lithography positioning techniques were needed during the device fabrication process due to the large area of as-grown atomic thin MoS2 films. As-obtained flexible photodetectors showed responsibilities of ～ 20 mA/W and response time of several seconds. This demonstrates the possibility of employing large-area two-dimensional semiconductors to meet the increasing demands for wearable and portable electronics.