Now days the engine manufacturers are concentrating more on reducing the engine emissions. For the reduction of these engine exhaust emissions, combustion system plays very important role. For effective combustion system, various parameters like combustion pressure,compression ratio,proper fuel mixing and ignition timing etc are very important. In this scenario, lot of research has been carried out on arriving at a piston design which can give effective fuel mixing,high compression ratio. Due to high market competition in automotive sector,it has become always important to produce components for minimum cost at the same time satisfying all the necessary requirements. So there is a need for the piston design which can give all the above said capabilities. At the same time, it should be light weight, low cost, structurally and thermally withstandable at very high pressure and temperature conditions that will occur in the combustion process.The objective of the project is to carryout multi-body dynamic analysis of IC engine assembly to investigate and analyze the stress distribution in piston at the real engine condition during combustion process and to optimize the weight of piston.