Because of its excellent power and economy in fuel, diesel is widely applied in recently years. Engine manufacturers are facing increasingly severe emission standards due to environmental concerns and desire for more efficient conversion from chemical energy to mechanical power. The crank linkage is one of the most important components of engine. It endures complex and various impact loads and it is the key point and difficulty of the engine design. The traditional design and analyze methods are so simple that they can not be satisfied with the actual demands, but the development of the reverse engineering and modeling software make possible that the response of crank linkage can be analyzed precisely. This paper has researched the combustion process in IC engine using the technology of computer simulation. Numerical modeling and experiment have been carried out on the diesel engine.