Abstract: In order to study the SO2 emission characteristics of coal combustion in a fluidized bed under oxygen-enriched combustion atmosphere,combustion experiments were carried out in a small fluidized bed reactor with lignite and anthracite as raw materials under 21%,29%,42% and 56% O2/CO2 atmosphere,respectively. The influence of combustion atmosphere on SO2 emission from fluidized bed coal combustion was investigated. The results show that with the increase of oxygen concentration,the SO2 emission of two different types of coal tends to increase gradually after combustion at 770 ℃ under the atmosphere of O2/CO2. The SO2 emission of lignite can increase from 925×10-6 to 6 526×10-6 by volume and that of anthracite can increase from 1 310 ×10-6 to 5 357×10-6 by volume. Compared with anthracite,the increasing trend of lignite is more obvious. The effect of oxygen concentration on SO2 precipitation rate is also obvious. SO2 precipitation reaches a higher peak value in 15 s or even shorter time. When the oxygen concentration increases from 21% to 29%,the transformation S increases significantly,and then with the increase of oxygen concentration,the transformstion S increases slowly. It is explained from the mechanism that the high oxygen concentration provides more oxygen for sulfide precipitation and promotes the formation of SO2. At the same time,the high oxygen concentration accelerates the combustion speed of volatile matter and char and improves the combustion and burnout characteristics of coal. By enhancing the self-heating effect of coal itself,the combustion process of coal is accelerated. Therefore,the release of sulfur element in coal is promoted and the emission of SO2 is correspondingly increased. With the increase of oxygen concentration,the CO of lignite remains at a relatively stable level,indicating that the change of oxygen concentration has little effect on it. Lignite has a high volatile content,so it is easy to be short of residence time,which leads to inadequate combustion and a certain amount of CO in the flue gas. The emission of SO2 is not only related to the concentration of oxygen,but also related to the sulfur content in coal. Generally,the higher the sulfur content is,the more SO2 produced by coal combustion is. The sulfur content of the coal involved in this paper is high,so the SO2 emission is at a high level. In the process of oxygen-enriched combustion,the SO2 emission control should be fully considered for the coal with high sulfur content. The ash also affects SO2 emission,Si O2 and Al2 O3 have little effect on SO2 to SO3,while Ca O and MgO have obvious effect. The content of Fe2 O3 and K2 O in coal ash also has influence on the transformation process.