Abstract: HCCI combustion mode is a combination of the modes of Compression Ignition (CI) and Spark Ignition (SI). A very short duration of combustion in HCCI resulted in faster pressure increases than that at the SI engine and even on the Compression Ignition Direct Injection (CIDI) engine. This research was aimed at finding the pressure distribution and CO-HC emission of the engine. They were predicted on two models, i.e., single zone and multi zone models. Multi zone model divides the cylinder into ten different zones and 3 K stratification temperatures. Two reaction mechanisms were implemented, i.e., detail mechanism and reduced mechanism. Thermodynamic equations of the species involving in combustion reaction were presented in polynomial function of specific heat coefficient, enthalpy and entropy within the temperature range. Reaction mechanism was determined based on arhennius coefficient and state equation was presented in multi-fluid ideal gas where the pressure and density of reactant were presented in the summations of pressure and density of species. The rate of progress reaction was defined as the difference between forward rates and reverse rates and the rate of progress species was defined as the summations of all the rate progress species involved in the reaction. Both models were simulated on the crank angles of 1650-1700 referring to the experiments of the other researchers. The simulation was conducted on five variations of equivalence ratio and was carried out using kinetic reactions based software. The results were presented in graphics comparison of experiment and simulation. Pressure distribution of the experimental and the simulation results on single zone model and multi zone model showed the same tendency on the reduced mechanism results in the higher equivalence ratio. The detailed mechanism on a single zone model gave closer results to the experimental one compared with the reduced mechanism. While CO-HC emission of the experiment under reduced mechanism simulation seemed fit quite well on the equivalence ratio of approximately 0.2 they, however, deviated far at higher equivalence ratio because the fuel, theoretically, gets enough air to burn perfectly.