Sealing system is an important subsystem of modern high-performance engine. Sealing system reliability directly affects the engine operating conditions. Cylinder head gaskets(CHG) sealing system is of the most importance to the engine sealing system, which is not only responsible for sealing chamber, the cooling fluid and lubricating oil passage, for preventing gas leakage, water leakage and oil leakage, but also responsible for force transferring between cylinder head and cylinder body. Basing on nonlinear solution method, the sealing performance of multi-layer-steel cylinder head gaskets to a gasoline engine is studied with the finite element software ABAQUS. The deformations of the cylinder liners and engine block are also considered. By setting up 3D model of cylinder head gaskets sealing system, setting up boundary condition, using gasket elements with load-deflection curves, the distribution of contact stress and strain on the cylinder head gaskets under pretension status and deformations of the engine block are obtained. The stress distribution rules of simulation fitted the experiment data well compared to the experiment result. Results show that: The minimum contact stress of the full bead on the cylinder port is greater than 50MPa and the minimum contact stress of the half bead on the oil hole is greater than 20MPa, which can meet the sealing requirements of the engine. Varied bead structure affects stress and strain distribution of cylinder head gaskets. The bead height has an effect on the contact stress and the bead width has an effect on the contact strain. Cylinder head gaskets also affect the deformations of the engine block, which should be taken into consideration in design.