The utility model provides an optical fiber sensing equipment for detecting storage tank oil -water interface relates to the oil field and measures technical field, and wherein this optical fiber sensing equipment passes through the different temperatures on different medium layers such as air in the real -time supervision oil storage tank, oil reservoir, emulsification layer, water layer to reach the effect of real -time, accurate monitoring profit liquid level. An optical fiber sensing equipment for detecting storage tank oil -water interface, includes: the vertical bellows of settling in the oil storage tank, the bottom of bellows is provided with horizontal base, the winding has armor temperature measurement optical fiber on the bellows, at least including 2 mutual spare multimode heat sensitive optical fiber among the armor temperature measurement optical fiber, still include in the optical fiber sensing equipment: temperature transducer and distributed optical fiber host computer, temperature transducer and distributed optical fiber host computer pass through multimode heat sensitive optical fiber interconnect.