Coal gasification with CO2rich gas mixture is one of several promising new technologies associated with CO2 reduction in the atmosphere. Coal gasification with high CO2 concentration is suitable for producing large amount of syngas. However, an increase in CO2 concentration will result in lower gas temperature in the reactor. In this paper, a similar gas temperature profile in CO2/O2 mixtures to that of coal gasification in air is predicted by observing the effects of CO2 concentration. The coal gasification model considered in this calculation is composed of devolatilization model, char gasification model and gas phase reaction model. Reaction rate equation of n-th order type with the Random Pore Model is applied to the char gasification reaction. Influence of inlet particles size is also studied. It is found that 20μm particles in 21%O2/79%CO2 and 100μm particles in air (21%O2/79%N2) result in a similar gas temperature profile during coal gasification. The outlet gas mixture with the same calorific value as from air blown coal gasification can be obtained if air is replaced by 50%CO2/29%N2/21%O2 mixtures.