The uniformity of EGR rate and intake quantity of each cylinder are the two most concerned problems of natural gas engine under stoichiometric combustion mode. For the conventional calculation method of EGR rate uniformity

the inlet ports of each cylinder are taken as the outlet boundary of calculation fluid domain. However

the intake quantity of each cylinder is a given value when the outlet mass flow boundary is adopted. Therefore

this method is only applicable to the analysis of EGR rate of each cylinder

not to the analysis of intake quantity of each cylinder. In order to solve the problem of calculating the intake quantity of each cylinder

a calcula-tion method considering the movement of multi-cylinder valves and pistons was established in this paper

which can not only directly calculate the intake quantity and equivalent ratio of each cylinder

but also obtain the parameters describing the flow state in the cylin-der such as vortex ratio

tumble ratio and turbulent kinetic. Moreover

this method enriches the parameters for evaluating the intake uniformity and expands the calculation ability. Finally

the intake uniformity of a China VI natural gas engine was analyzed by the above method.