A four-stage hydraulic cylinder is used as the actuator in a large tonnage erect and withdraw hydraulic system. When changing its stage, the multi-stage cylinder has a impact phenomenon because of the mutations of its area. Since the rod chamber of the multi-stage cylinder without a throttling and cushioning structure, so a method of controlling the balance valve throttling is used to ease the impact.The throttling flow characteristics of the balance valve directly affect the stability of the withdraw hydraulic system.A main spool structure with a multiarea gradient was proposed through the theoretical calculation and the simulation analysis of AMESim. The effect of pressure drift on the opening of the main valve was solved.The correctness of this structure is verified by the valve and system test.The inconsistent problem of the opening of the balance valve is eliminated,the state consistency of the volume production is ensured, the fault tolerance of the balance valve to characteristic change of the system is improved effectively.