Multi-dimensional transient numerical simulation was done for induction, compression, combustion process of YD490ZL diesel engine by AVL_Fire. The gas flow, heat transfer in cylinder wall, fuel spray, particle formation and so on in different time of entire working process were analyzed for providing certain reference for optimization design of diesel engine cylinder. Combustion will be more sufficient and fuel economy will be higher if the relative distance between the center of combustion chamber and cylinder at X direction is adjusted. The heat transfer coefficient changes with the space position as well as time. The distribution of heat transfer coefficient and temperature at different time and position was provided by multi-dimensional transient calculation which provided the best boundary condition for finite element calculation. Intake swirl was formed obviously during the intake process; ring movement of gas flow in combustion chamber was still existed near the top dead center while it was influenced by squish flow.