Mechanical characteristics of the component in ultra-high pressure hydraulic jacking system are the main factor that affects its performance,which are the key challenges in UHP technology.The FEM was used to research the change rules of the hydraulic system stiffness,modal,natural frequency,displacement and stress under different material,diameter and thickness of each component in ultra-high pressure hydraulic jacking systems.The finite element calculation results are relatively close to the pressure test results，which verified the effectiveness of the finite element model and boundary conditions.The results show that the hydraulic spring stiffness is increased with the increase of inner diameter of cylinder,but decreased with the increase of amplitude,the effect is decreased with the increase of inner diameter;the system natural frequencies before the 3rd are increased with the increase of ground strength;the threshold stress in Bonded conditions is minimum,but it is maximum in Frictional condition,ultimate stress is decreased with the increase of ground stress;the maximum displacement is increased with the increase of frictional coefficient,the maximum stress is increased with the increase of ground strength on the C20 ground;the maximum displacement first increases and then decreases with the increase of frictional coefficient on the C30 ground,the critical frictional coefficient values on displacement and stress are 0.43,0.59 respectively;the ultimate displacement is significantly reduced by structural steel surface;the ultimate difference of displacement increases with the ground stress in the same length of hydraulic cylinder of different side;the ultimate stress of hydraulic cylinder bottom increases with the increase of ground stress,the displacement of hydraulic cylinder in sideⅡis larger than sideⅠ,the ultimate displacement is closer to the top,and the extreme value is alternating.The study investigates the stress and strain of hydraulic jacking apparatus under ultra-high pressure,providing references on design of its structure,seal and applications.