The causes of vibration of relief curved lid printer at high working speed were analyzed. It was pointed out that the vibration of host machine was related with eccentricities of the transfer drum and the gap of leadscrew nut mechanism. A pneumatic damping mechanism which could eliminate the gap of leadscrew nut mechanism and could damp the vibration was designed. The vibration of host machine is greatly reduced when the mechanism is used, the damping effect is superior to the rigid gaps eliminating mechanism such as open-close nut mechanism and double nuts mechanism.