The utility model relates to an air door valve opening degree detection unit and a monitoring device, and belongs to the field of coal mine ventilation detection. The technical problem to be solved isto provide the air door valve opening degree detection unit and the monitoring device which are relatively low in cost and simple and convenient to operate. The technical scheme for solving the technical problem is as follows: the technical scheme is adopted; the utility model discloses an air door valve opening detection unit. Wherein the light emitter and the light receiver are oppositely arranged on the inner walls of valve bodies at the two ends of an air door valve baffle in the direction perpendicular to a baffle rotating shaft. The distance between the connecting line of the light emitter and the light receiver and the baffle rotating shaft is not larger than the radius of the air door valve baffle, and the light signal input end of the controller is electrically connected with theoutput end of the light receiver. The real-time opening device can be widely applied to the field of real-time opening of the air door valve.