The main form of damage to the connecting rod is fatigue fracture and excessive deformation. Usually the location of fatigue fracture is three high stress areas on the connecting rod. The working conditions of the connecting rod require the connecting rod to have high strength and fatigue resistance; and it is required to have sufficient rigidity and toughness. In the traditional connecting rod processing technology, the material is generally 45 steel, 40Cr or 40MnB and other quenched and tempered steel, the hardness is higher. Therefore, the new connecting rod materials produced by German auto companies, such as C70S6 high carbon microalloy non-tempered steel, SPLITASCO series Forged steel, FRACTIM forged steel and S53CV-FS forged steel (all above are German din standards). Although alloy steel has high strength, it is sensitive to stress concentration. Therefore, in the shape of the connecting rod, excessive rounding and other aspects of strict requirements, should also pay attention to the surface processing quality to improve the fatigue strength, otherwise the application of high-strength alloy steel can not achieve the expected results.