Combustion and emission characteristics of burning of No. 6 residual oil with the additive of 100ppm of organic barium are investigated in a can combustor test rig. The effects of the additive on the flame structure and formation of pollutant are examined at a fixed fuel air ratio of 0.02. With Beckman/Rosemount gas analyzer and Roseco engine smoke emission sampler, the exhaust pollutant and particulate were measured. Temperature distribution inside the combustor was employed to assess the flame structure. Emission of CO and particulate of the oil with additive combustion are found about 25% and 40% less than those of pure oil combustion. The emission of NO is, however, observed not much difference between two test cases. A longer and wider flame zone is found in the case of burning oil with the additive of organic barium.