In this study, comparative combustion was performed in a 3-ton flue tube boiler for emulsified oil manufactured by using 15% water and approximately 1% carbide aqueous solution as an emulsifier in Bunker-C oil, and the characteristics of exhaust emissions were analyzed. As a result of performing comparative combustion under the same ambient environment and external conditions, the exhaust gas temperature decreased by approximately 3.93% from 183.76℃ for bunker-C to 176.52℃ for EM15, and the oxygen concentration increased by approximately 2.96% from 9.72% to 12.68% . Carbon dioxide decreased by approximately 2.3% from 8.49% for bunker-C to 6.19% for EM15, indicating that EM15 has a greenhouse gas reduction effect. When the standard oxygen concentration of 4% was applied, nitrogen oxides decreased by approximately 43.17% from 130.59 ppm for Bunker-C to 74.21 ppm for EM15, and sulfur oxides decreased by approximately 53.05% , confirming the excellent emission reduction characteristics of emulsified fuel oil. Therefore, it is expected that replacing emulsified fuel oil in boilers using Bunker-C oil will enable response to increasingly strengthened emission regulations.