In recent years, two-dimensional materials have demonstrated excellent optoelectronic response capabilities at the atomic scale, and material systems based on two-dimensional materials have become an important component in the field of optoelectronic detectors. In terms of device structure, the fabrication of heterojunctions is an effective strategy for optimizing the performance of two-dimensional photodetectors. Its advantage lies in combining two or more materials with different band structures at the atomic or nanoscale; the resulting built-in electric field effectively promotes the separation and transport of photo-generated carriers. Transition-metal chalcogenides have attracted widespread research attention in the field of low-dimensional optoelectronic devices due to their intrinsic physical properties, including atomic-scale thickness, high carrier mobility, tunable bandgap, and strong light-matter interactions. This article proposes a broad-spectrum, polarization-sensitive photodetector for the visible to near-infrared range based on a SnSe2/MoWSe4 heterostructure. Due to the anisotropy of MoWSe4, its heterogeneous integration with SnSe2 forms a van der Waals heterojunction, enabling both wide-band detection and polarized light detection capabilities. The resulting built-in electric field promotes the separation and transport of photo-generated carriers, thereby enhancing the device′s overall performance. The device′s response band extends from the visible to the infrared (532~1550 nm). Under a 532 nm laser, it exhibits a responsivity as high as 51.5 A/W and a specific detection rate of 6.9×1010 Jones. Its excellent external quantum efficiency (12 010%) and fast rise and fall response times of 3.5 ms and 19 ms, respectively, demonstrate its outstanding optical performance. Furthermore, the device exhibits an anisotropy ratio as high as 8.8 under a 532 nm polarized laser, and an anisotropy ratio of 6.7 at 976 nm, highlighting the potential of the SnSe2/MoWSe4 heterojunction as a polarization-sensitive detector and providing new design insights for the development of a new generation of high-performance, wide-bandwidth polarization-sensitive optoelectronic devices.