Abstract: To explore the combustion characteristics of liquid fuel moderate and intense low-oxygen dilution（MILD） combustion, the MILD combustion process was investigated by numerical simulation, and the effects of air and fuel inlet conditions on flue gas reflux ratio, flow field and pollutant emission were analyzed in detail. The results show that the flow field structure in MILD combustion chamber plays a decisive role in fuel air mixing.With the increasing of equivalence ratio, the combustion chamber temperature is increased accordingly with increased CO emission, and the NO_x emission is also increased. When the equivalence ratio is 0.9, the emission of NO_x reaches a peak value. With the increasing of air inlet velocity, the temperature distribution on the central surface of the combustion chamber is uniform without obvious local high-temperature peak point, and the NO_x emission is decreased, while the CO emission is decreased with latter increasing. The emission of CO is the lowest when the air inlet velocity is 110 m/s. With the increasing of fuel inlet velocity, the peak temperature in the combustion chamber is increased with increased NO_x emission, and the CO emission is decreased with latter increasing.