The dynamic analysis is used to design an effective buffer for rotatingbarrels machine gun. The designed buffer can mostly reduce the recoil force when the gun is firing and increase the hitting precision to some extent. The adoption of hydraulic pressure buffer with a valvereversing spring can remarkably refrain the recoil length and at the same time mostly reduce the recoil force. It is an effective way for rotatingbarrels machine gun to realize low recoil force.