In a certain hydraulic system,main impact factor to cylinder internal leakage is cylinder twochamber differential pressure.In the state that cylinder load was held,the simulation model was built.The simulation results show that the decline rate of the inverted installation is faster than that of the normal installation.In the normal installation,cylinder will stop at a certain position due to twochamber pressure difference eventually disappearance.But in the inverted installation,cylinder will continue to decline due to always existing pressure difference between twochamber.So in the device design,using the normal installation is better.