To　improve　the　jumping　performance　and　reduce　the　modeling　complexity,　a　pneumatic　wheeled　typed　jumping　robot　is　designed,　the　takeoff　angle　of　which　can　be　adjusted　while　it　starts　jumping.　The　double-acting　cylinder　with　the　power　source　of　liquid　carbon　dioxide　is　used　as　jumping　mechanism.　The　changes　of　the　precise　equations　of　the　internal　pressure　in　the　cylinders　are　established　and　a　cylinder　hopping　model　is　built.　The　jumping　simulation　and　the　movement　of　process　of　the　cylinder　are　performed.　Results　show　that　the　actual　characteristics　of　movement　of　the　cylinder　agree　with　the　simulation　ones.