Abstract: To determine the technical parameters of the mobile enclosure facilities, the flowing laws of the leaking oil of oil tank in the tunnel of cave storage were investigated in this paper. Based on the theory of open-channel unsteady flow, a physical model for describing the flowing behaviors of oil in the tunnel of cave storage was developed, and its numerical solution under the given initial conditions and boundary conditions were obtained by means of characteristic line method. The variation laws of the depth and flow rate of the leaking oil in the tunnel over the leaking time were figured out. In addition, the effect of leaking rate on the flow of oil was researched. It is indicated that as the leaking rate increases, the flow rate, depth and flowing distance of leaking oil in the tunnel increase. What's more, the farther it is from the leaking tank, the less different the depth and flow rate of leaking oil at different flow rates are. The research results provide the technical support for the optimal installation of mobile enclosure facilities used for oil leakage in oil depots.