Aiming at the abnormal leakage problem of the north sluice of the Shilianghe Reservoir, based on a long series of field synchronous prototype observation tests, the temperature field around the secondary stilling basin of the north sluice was drawn.The similarity and dissimilarity characteristics of mass concentrations of hydrochemical elements such as Ca2+ and Cl^- were analyzed. The main source and leakage path of the secondary stilling basin of the north sluice were identified, and feasible reinforcement measures such as building underground continuous cut-off wall, using high-pressure jet grouting pile to intercept seepage, and repairing the bottom filter of the secondary stilling basin were put forward, which made the reinforcement project be constructed accurately, blocking the leakage passage successfully and great economic benefits were achieved. The results of the Shilianghe Reservoir dam leakage detection show that the combined tracing method of temperature field tracing, natural water chemical tracing and ICP chemical tracing can accurately trace the source of leakage, it can be promoted and applied in dam leakage detection.