In order to obtain cushion characteristic regularity to change each parameters, Based on dynamic equations, thermodynamics equations and flow equation of venting orifice, an analytical model has been built up and validated by Hyperworks. Then, based on the model, the deceleration characteristic was investigated. A series of simulations were conducted to find out the influence of cushioning characteristics, such as volume ratio of slaver-master, initial pressure and venting orifice area. The initial inflation pressure also is a key parameter to affect the cushioning properties, and the maximum deceleration decreases with increase in initial inflation pressure, but at the same time the ending velocity of the heavy equipment will have a tiny increase; If the venting orifice area is too small, the airbag will rebound because the impact energy can’t be released in time; but if the venting orifice is too large, the ending velocity of the heavy equipment will exceed the limitation because no enough impact energy is transferred to the airbag attenuation system.