Since the Kyoto Protocol became into effect, Korea has been expected to be part of the Annex I countries performing the duty of GHG reduction in the phase of post-Kyoto. Therefore, it is necessary to develop emission factors appropriate to Korean circumstances. In order to develop emission factors this study utilized the CleanSYS, which is the real-time monitoring system for industrial smoke stacks to calculate the emission rate of continuously. In this study, the main focus was on the power generation plants emitting the largest amount of among the sectors of fossil fuel combustion. Also, an examination on the comparison of emission was made among 3 generation plants using the different types of fuels such as bituminous coal and LNG; one for coal and others for LNG. The concentration of the coal fired plant showed Ave. 13.85 %(10,384 ton/day). The LNG fired plants showed 3.16 %(1,031 ton/day) and 3.19 %(1,209 ton/day), respectably. Consequently, by calculating the emission factors using the above results, it was found that the bituminous coal fired power plant had the emission factor average of 88,726 kg/TJ, and the LNG fired power plants had the average emission factors of 56,971 kg/TJ and 55,012 kg/TJ respectably which were similar to the IPCC emission factor.