Abstract: In recent years, photodetectors have been widely applied to imaging, sensing, optical communication, biotechnology and other fields. It is urgent to fabricate photodetectors with high performance and low energy consumption by a simple preparation method. In this paper, two-dimensional GaSe, MoS₂ and graphene were prepared by the mechanical exfoliation. Then, the GaSe/MoS₂ vertical van der Waals heterostructure photodetector was fabricated by transferring GaSe、MoS₂ and graphene onto the Au electrode in turn. At a bias of 2 V, the photodetector has a responsivity of 351 mA/W to 450 nm light, a detectivity of 1.18 × 10⁹ Jones, and an external quantum efficiency of 97%. Limited by the band-gap of GaSe, the device has a high responsivity only to the light with wavelength less than 620 nm. At a bias of 0 V, the photodetector also can detect 450 nm light repeatedly, and the response speed is fast. The response time and the recovery time are 0.36 s and 0.24 s, respectively. The outstanding performance of the photodetector is attributed to the type-Ⅱ vertical van der Waals heterostructure, indicating that the heterostructure has a great potential in the fabrication of high-performance and low-power photodetectors.