This paper presents an optimization of CHP and thermal storage to maximize the profit of district heating company under electricity and thermal conditions, especially in Korea. The objective of optimization is to find the optimal electrical/thermal output and operation modes of CHP, and scheduling of thermal storage. Each operation mode of CHP is defined and modeled mathematically, and the physical and actual operational aspects of CHP are also considered. This paper studies a case to show the effect on profit of company according to the thermal storage.