The percentage of the coal-fired power plant in Indonesia is still dominant. Types of boilers used include boiler stockers, circulating fluidized bed boilers, and pulverized boilers. Based on the coal combustion burner layer, the pulverized boiler uses a front-rear and tangentially fired boiler type. The results of tangentially fired boilers are more perfect because the flow of turbulence is produced. Properties of coal also affect the level of perfection of the combustion process that occurs and the heat distribution in the boiler. The boiler initial design of Suralaya 8 Coal Fired Steam Power Plant that uses LRC will operate all boiler support equipment at full load, this will reduce boiler reliability. To improve the reliability of the boiler, it will be studied with LRC mixed with MRC which has a higher quality and calorific value so that at full load will reduce the load of boiler support equipment. So from that research is needed regarding the combination pattern and the entry of LRC and MRC coal at the proper burner elevation to produce more perfect combustion, there is no change in temperature distribution in the boiler, low unburn carbon without neglect the economical aspect of the plant operation. This numerical study uses the Computational Fluid Dynamics (CFD) method. Making boiler geometry using Gambit 2.4.6 software and numerical simulation using ANSYS Fluent 16.0. The simulation includes the standard turbulence k-ϵ model. The material uses LRC and MRC with the provision of MRC inclusion at the bottom burner and LRC elevation above. Boundary condition uses the inlet velocity for primary and secondary air nozzle, CCOFA, and SOFA. Coal injection as mass flow inlet. The outlet parameter is a pressure outlet, a heat exchanger as a porous medium that has a heat generation. Waterwall tubes as walls that have heat fluxes. The results of this study will show simulation results and analyze changes in heat distribution in boilers to boiler performance, exhaust emissions and economic studies of mixing MRC in LRC with variations in the inclusion of MRC at 1 and 2 burner layer coal. Accuracy of simulation models was established by carrying out a comparison with real-life data.