The invention discloses an m-surface ZnOS thin film-based spontaneous polarization enhancement photoelectric detector and a fabrication method thereof. The detector sequentially comprises an m-surfacesapphire substrate, an m-surface ZnOS thin film layer and a pair of parallel metal electrodes from bottom to top, wherein the parallel metal electrodes are perpendicular to a c-axis direction of a ZnOS thin film. In the photoelectric detector, the internal polarization field can be overlapped with an external electric field when an electric field applied onto an electrode is same as the directionof a spontaneous polarization field, the carrier separation and transmission is synergically improved, and the response speed of the photoelectric detector is effectively improved. Moreover, the fabricated photoelectric detector is of MSM construction and is simple in structure, and the fabrication process is also simple, is low in fabrication cost, is easy to produce and is beneficial for industrial application.