GT-Power software was used to establish the simulation model of a locomotive diesel engine

and the simulation model was verified by tests. Simulation cases were developed to study the influences of two kinds of Miller cycle on engine power

fuel consumption and emissions at 1 000 r/min with different loads

and the effects of these two kinds of Miller cycle were compared at full load. The study shows that both kinds of Miller cycle can decrease NOx emissions. In terms of engine performances

the Miller cycle with modified intake cam profile and with intake valve lift profile moved by 30 degrees of crank angle is selected as an optimization plan for the locomotive diesel engine. This proposal can give guidelines to further researches on the application of Miller cycle to locomotive diesel engines.