Beijing, the capital of China, revised the emission standard of air pollutants for boilers in the year of 2015. To promote the boilers to meet the new standard, the “coal to gas project” and the “reward replaces subsidy policy for low-NOx retrofits of boilers” were implemented recently. Therefore, the emission of pollutants from boilers has been significantly changed in Beijing. In this study, a comprehensive unit-based emission inventory of multiple air pollutants, including PM10, PM2.5, CO, SO2, NOx, VOCs and NH3, from both coal-fired and gas-fired industrial boilers in Beijing in 2015, was established with annual activity and category-specific emission factors. Based on the limitation of the revised emission standard, scenario analysis and CMAQ model were used to forecast the environmental impacts of the revised standard in the heating season of Beijing. Our results showed that, in 2015, the emissions of CO, NOx, PM2.5, PM10, SO2, NH3 and VOCs from the industrial boilers in Beijing were about 51745 t, 27943 t, 10143 t, 14624 t, 20227 t, 197.55 t and 1304 t, respectively. Coal-fired boilers were the major source of CO, SO2, PM2.5 and PM10, while gas-fired boilers were the major source of VOCs and NH3. Besides, in IPC-1 and IPC-2 scenarios, which represent the different levels of the implementation of “low-NOx retrofits policy” as well as all coal-fired boilers being replaced by gas-fired boilers, the ambient concentration of PM2.5 and SO2 reduced about 7.1% and 9.5%, respectively, and the concentration of NO2 reduced about 4.4% in IPC-1 and 3.7% in IPC-2 in the heating season of Beijing.