Since Tad McGeers work in the late 1980s, passive dynamic walking has received special attention.M.Garcia introduced the simplest walking model which can walk down a shallow slope passively [1].M.Wisse and E.Borzova respectively proved that the walking models with upper body can also walk stably [2, 3].And the 3D passive walker is fully considered [4-6]Damping is unavoidable in Engineering.