A methematical model was studied to predict flow rate, heat transfer and heat of combustion in rotary kiln incinerater. For the design of equipments and for the optimum operating conditions, it is necessary to understand the combustion status such as the transient temperature distribution and the degree of combustion. The objective of this study is to establish the combustion model that can be used for design and performance evaluation of incinerator. And also, numerical analysis to be able to understand heat transfer phenomena in the rotary kiln incinerator was performed in this study.