Frictional characteristics of rubber Orings at high gas pressure were studied experimentally.The influence of seal pressure,compression ratio and rubber materials on the friction performance of the Oring was analyzed when the seal pressure was greater than 3 MPa.The experimental results show that the timevarying curves of Orings friction force and displacement under high pressure and low pressure are similar,with an obvious hysteresis characteristic.With the increasing of sealing pressure under high pressure condition,the maximal friction and sliding friction of Nitrile rubber Oring are increased linearly,which is different from the calculated results under low pressure condition that the maximal friction exists maximum and the sliding friction tends to be stable.Under the condition of high pressure,the maximal friction of rubber Oring has a nonlinear relation with the compression rate,and the maximal friction exists maximum,which is also different from the calculated results under low pressure condition that the maximal friction is increased with the increasing of compression ratio.The friction of EPDM rubber,Silicone rubber and Fluorine rubber is less than that of Nitrile rubber,and it is increased with the increasing of sealing of pressure and tends to be stable,which is different from the Nitrile rubber.