In this work, a dense γ-In2Se3 nanosheet array has been fabricated using the chemical vapor deposition method under atmospheric pressure. Compared with crystal silicon, the photodetector based on the γ-In2Se3/p-Si heterojunction exhibits a high responsivity (96.7 mA W-1) at the near-infrared region, a presentable current on/off ratio (∼1000) and excellent detectivity (2.03 × 1012 jones). Simultaneously, the obtained photodetector demonstrated a fast response speed (0.15 ms/0.5 ms) and a broadband sensitive wavelength from ultraviolet (340 nm) to near-infrared (1020 nm). The photoelectric experimental data of the device shows that its high performance is attributed to the high-light absorption capacity of the material, the rational energy band structures of γ-In2Se3 and p-Si, and the effective separation of photo-generated carriers caused by the formed type-II heterojunction. Our work provides the primary experimental basis for the photodetection application of the γ-In2Se3 nanostructure.