Considering the piston secondary motion,a dynamics model of cylinder-piston ring in engine which involving solid particles was built to study the motion of piston ring.The gas with solid particles was regarded as the mixture gas,and the gas flow equation was modified.The influence of particles on piston ring dynamics,gas flow in ring groove and blow-by was studied.The results show that the piston ring twist is significant increased when the particles are present and the gas flow in the ring groove is increased,which leads to blow-by increase and has an adverse effect on the engine performance.