The invention relates to a probe module which consists of a light guide full-optical-fiber probe, a pair of fixing bolts, a lens group, a distance-adjustable metal sleeve, a probe seat and a reflecting mirror surface, wherein a probe seat is fixed on the light guide full-optical-fiber probe; an underwater measurement optical fiber is fixedly connected onto the probe seat; the measurement optical fiber is connected to the lens group; the reflecting mirror surface is fixed at the bottom of the distance-adjustable metal sleeve; the fixing bolts fix the distance-adjustable metal sleeve on the probe seat. By the adoption of a full optical fiber for replacing a fixed measurement light path, the probe module is high in detection sensitivity and convenient for test and can realize on-line detection.