Abstract: As the supporting wall of deep foundation pit, diaphragm wall has good strength and safety stability. But the incompleteness of the wall will cause the leakage problem and seriously affect the function of the wall. Aiming at the leakage problem of diaphragm wall, a model experiment is designed to explore the temperature rise stability of concrete with different mud content under different pressure power and time. Through the abnormal points in the temperature rise curve, the integrity of the wall and the leakage of the wall can be analyzed. Distributed temperature sensing (DTS) based on distributed optical fiber is proposed. The detection method of concrete pouring integrity of diaphragm wall and the prediction method of leakage at the joint of diaphragm wall are proposed. Taking the deep foundation pit diaphragm wall project of Kunming Metro Line 4 as an example, the sensing optical cable and its layout method for monitoring the leakage of diaphragm wall are introduced by using DTS. The feasibility and effectiveness of this method are verified by comparing the detection results with the actual leakage situation.