The article describes the possibilities of optimization of combustion processes at waste incineration, which require a specific approach in comparison with conventional fuels. The main cause is an instability of thermo-chemical properties of majority of waste. The work defines and evaluates criteria, which are critical for the waste incineration process. The numerical model Combustion temperature for optimization of thermal work of the waste incinerator was designed for support of implementation of other measures aimed at increasing the process energy efficiency, and it was verified in practice in real waste incineration plant.