Abstract:A Oring performance testing device used in the static ring was developed.By using step motor to apply the axial load on the core axes through differential screw mechanism,this device can give pressure to the Oring in four directions,and then simulate the Oring seal between the static ring and the static ring seat.The contact stress and leakage of Nitrile rubber Oring under different working conditions were measured based on the device.The results show that,under certain precompression rate,the contact stress of Oring is increased with the increase of working medium pressure;In the case of certain working medium pressure,the contact stress of Oring is decreased with the increase of the precompression ratio,but the decreased amplitude is not so large.The inner diameter of the Oring has some effect on the contact stress under different conditions,but the influence is not big.