With the increase of exploration depth,formation pressure rises and rock hardness increases,screw drilling tools often experience lateral whirl,longitudinal bounce,torsional vibration and stick-slip phenomena,which limit the popularization and application of impact screw drilling tools.In order to study the sealing characteristics and parameter sensitivity of the transmission shaft assembly under the coupling effect of high temperature,high speed and reciprocating motion,the sealing characteristics of star rings,O-rings and combined rings under the same working conditions were compared,and the contact pressure distribution of different sealing rings in static and dynamic sealing states was obtained.The best sealing ring structure was determined according to the method of determining the contact pressure of the main sealing surface.Based on this structure,the sensitive parameters of the groove were studied,and the influence of the groove shape,position,number and width on the sealing characteristics of the combined ring was discussed.The results show that the sealing effect of the combined ring is far better than that of the O-ring and the star ring.When the groove shape is isosceles triangle and the number of grooves is 3,the sealing performance is the best,and the groove position in the middle is the most reasonable.In the static and dynamic sealing state,the contact pressure of main sealing surface increases with the increase of the groove width,while the contact pressure of secondary sealing surface in the static sealing state and the stress of O-ring is almost unchanged.