An optical path correction subassembly, an optical detection assembly, and an optical detection system are provided. The optical path correction subassembly can be optionally configured to be applied to a light detector. The optical path correction subassembly includes a holder structure and an optical path correction structure carried by the holder structure, and the optical path correction structure has a light beam guiding surface arranged as a reverse inclination inclined relative to a vertical line. The light beam guiding surface of the optical path correction structure can be configured to effectively or accurately guide a predetermined light beam to a light receiving surface of the light detector so as to facilitate collection of the predetermined light beam. The light beam guiding surface of the optical path correction structure can be arranged at an acute angle relative to the light receiving surface of the light detector.