Abstract: MoS₂ thin films were prepared on GaAs substrate by magnetron sputtering method to form GaAs/MoS₂ heterojunction.The thickness of the thin films was controlled by controlling the time of magnetron sputtering.The photoelectric properties of GaAs/MoS₂ heterojunction are also studied.The results show that the performance of the device is the best when the sputtering time is 20min and the film thickness is 300nm, the responsivity and specific detection rate of the photodetector are 0.107AW^-1 and 3.13×10¹¹Jones.The device has good response to the wavelength of 405nm to 980nm, and the prepared device is suitable for near infrared light detection.