Mixture homogeneity plays a crucial role in HCCI engine. In the present study, the mixture homogeneity was analysed by threedimensional engine model. Combustion was studied by zero-dimensional single zone model. The engine parameters studied include speed, injector location, valve lift, and mass of fuel injected. Valve lift and injector location had less impact on mixture formation and combustion phasing compared to other parameters. Engine speed had a noticeable effect on mixture homogeneity and combustion characteristics.