Piston ring is used to embed the piston groove inside the metal ring, piston ring is divided into two types: compression ring and oil ring. The compression ring can be used to seal the combustible gas mixture in the combustion chamber; The oil ring is used to scrape excess oil from the cylinder. The piston ring is a metal elastic ring with a large outward expansion deformation, which is assembled into the profile and its corresponding annular groove. The reciprocating and rotating piston ring, depending on the pressure difference of the gas or liquid, forms a seal between the outer circular surface of the ring and the cylinder, and between the ring and one side of the ring groove. Piston ring is the core component of fuel engine, it and cylinder, piston, cylinder wall together to complete the fuel gas seal. Commonly used car engine has two kinds of diesel and gasoline engine, due to the different fuel system performance, the piston ring its use is endless also and same, early piston ring formed by casting, but with the progress of technology, steel high power piston ring was born, and with the engine functions, environment asks is ceaseless rise, all kinds of advanced surface treatment and application of them, such as thermal spraying, plating, chrome plating, Gas nitriding, physical deposition, surface coating, zinc manganese phosphating treatment, so that the function of the piston ring greatly improved.