[en] Cone seal structure is widely used in metal tube connection of industrial equipment and ground vehicle. In vibration environment, the leakage failure of cone seal occur frequently, which will affect the function and reliability of the product directly. In this paper, the contact stress for typical cone sealing structure in low pressure metal tube under vibration loading is analyzed and the mechanism of liquid leakage failure is discussed using the finite element numerical method. Results show that the circumferential contact stress distribution is uneven on the interface of cone sealing structure under the cyclic load introduced by local vibration. The contact stress is significantly lower than the initial pretension stress in some areas, which will result in the leakage failure of cone sealing structure. (paper)