WtE of MSW plays a crucial role in renewable energy production in Korea. Municipal solid waste (MSW) is an important energy resource for combined heat and power (CHP) production. This study investigated an increasing method to the power generation efficiency by MSW to energy (WtE) plants in South Korea and discussed the issues related to energy efficiency improvement. In some cases, however, achieving a high energy efficiency of WtE is not practical due to various technical and non-technical reasons. The design and operation of a WtE plant is determined primarily by the amount of MSW to be treated, not by energy demand. The majority of these new facilities feature a very high efficiency with respect to both energy recovery and environmental performance. But they not only recover energy from waste, they also have the potential to facilitate a high material recovery. With their high energy efficiency they contribute even more to the reduction of greenhouse gases than earlier generations of WtE facilities. It is important to have this in mind in the strategic planning of both waste handling and energy production. Improving power generation efficiency is required for new power plants producing steam at pressures higher than the current level of 20-30 bar.