The photogating effect based on the vertical structure of a two-dimensional material allows high-sensitivity and broad-spectrum photodetector. A high-sensitivity photodetector based on the vertical heterostructure of indium selenide （InSe）/molybdenum ditelluride （MoTe₂） is reported， which exhibits excellent broad-spectrum detection capability from 365 to 965 nm. The top layer of InSe was used as the grating layer to regulate the channel current， and MoTe₂ was used as the transmission layer. By combining the advantages of the two materials， the photodetector has a fast response time of 21.6 ms and achieves a maximum detectivity of 1.05 × 10¹³ Jones under 365 nm laser irradiation. Under the illumination of 965 nm， the detectivity still achieves the order of 10⁹ Jones. In addition， the InSe/MoTe₂ heterostructure exhibits an external quantum efficiency of 1.03 × 10⁵ %， demonstrating strong photoelectric conversion capability.