Municipal waste incinerating facilities which were established before implementing the separate collection of garbage policy have operational problems due to high calorific power of separated waste. Although MBT(Mechanical Biological Treatment) systems are installed at incineration facilities in waste to energy aid, it is ineffective on existing incinerators. Therefore, this study aims to suggest the method for solving the calorific power problems and waste to energy of existing incinerators. In this study, High calorific waste was separated by MBT system and low calorific waste was incinerated at the existing incinerator. By this way, the existing incinerators were steadily operated without calorific problems.