Abstract: To make the stiffness of suspension adapt to different load, a new type of twin-accumulator hydro-pneumatic balanced suspension was proposed and its mathematical model was built up. Then the design principles and methods of its accumulators' parameters were proposed and proved through an example. The result indicates that, by appropriately matching the parameters of accumulators, such kind of balanced suspension can change the stiffness of suspension of multi-spindled vehicles properly and keep the same offset frequency under different load, thus the vibration performance of vehicles is improved.