In this paper, an ecological-based numerical analysis and optimization have been carried out for an air-standard irreversible Dual-Miller cycle engine with late inlet valve closing version using the ecological coefficient of performance (ECOP) criterion which covers finite rate of heat transfer, heat leak and internal irreversibilities. A detailed computational analysis has been performed in order to examine the general and optimum performances of the cycle. The results obtained based on ECOP function are compared with a different ecological function and with the maximum power output conditions. The consequences of ECOP, ecological function and maximum power output conditions are acquired based on the compression ratio, cut-off ratio, pressure ratio, Miller cycle ratio, source temperature ratio and internal irreversibility parameter. The influences of these parameters on the optimum performances are examined in detail.