For the sake of the hydraulic jacking device can provide enough sealing force, taking the disc spring in hydraulic device as the research object. On the basis of the size specification of disc spring in GB/T 1972—2005, series A disc spring was superior to series B and C in free height and other factors. Meanwhile, taking into account the influence of friction, the load displacement characteristic curve of series A disc spring was obtained. It is found that the displacement of disc spring increases sharply when it is close to 80% of the flattened state due to the bending of the section under load, and it has positive stiffness. Then different number n of parallel disc springs and number i of series groups of composite disc spring combinations were studied by ANSYS and the stress distribution of the disc spring group was obtained. The maximum stress of disc spring group is located at the place where the inner hole of the upper surface under the load.After that, the stress linear evaluation of the different combinations that met the service conditions were analyzed. It is finally determined that when 6 pieces of disc spring are stacked into a group and 5 groups are paired has the better performance and can be safely used under 3 600 kN sealing force.