Controllable synthesis of high quality large area monolayer MoS2 is still a challenge for its practice application. In this work, we report an Au foil assistant synthesis large size (400 μm) single crystals MoS2 on quartz substrate via chemical vapor deposition (CVD). The Raman and photoluminescence spectroscopy studies indicate the synthesized monolayer MoS2 has a high homogenous optical characteristic. The optoelectronic performance of MoS2 photodetector were also fabricated which shows a high photo-response of 550mA/W and a fast photo-response time of 230 ms. The growth techniques described here will beneficial for other atomically thin TMD materials growth.