<p>The Beijing-Tianjin-Hebei (BTH) region is a metropolitan area with the most severe fine particle (PM<sub>2.5</sub>) pollution in China. Accurate emission inventory plays an important role in air pollution control policy making. In this study, we develop a unit-based emission inventory for industrial sectors in the BTH region, including power plants, industrial boilers, and steel, non-ferrous metal, coking, cement, glass, brick, lime, ceramics, refinery, and chemical industries, based on detailed information for each enterprise, such as location, annual production, production technology/process and air pollution control facilities. In the BTH region, the emissions of sulfur dioxide (SO<sub>2</sub>), nitrogen oxide (NO<sub>x</sub>), particulate matter with diameter less than 10 μm (PM<sub>10</sub>), PM<sub>2.5</sub>, black carbon (BC), organic carbon (OC), and non-methane volatile organic compounds (NMVOCs) from industrial sectors are 869 kt, 1164 kt, 910 kt, 622 kt, 71 kt, 63 kt and 1390 kt in 2014, respectively, accounting for 61 %, 55 %, 62 %, 56 %, 58 %, 22 % and 36 %, respectively, of the total emissions. Compared with the traditional proxy-based emission inventory, much less emissions in the high-resolution unit-based inventory are allocated to the urban center because of the accurate positioning of industrial enterprises. We apply the Community Multi-scale Air Quality (CMAQ) model simulation to evaluate the unit-based inventory. The simulation results show that the unit-based emission inventory gives better performance of both PM<sub>2.5</sub> and gaseous pollutants than the proxy-based emission inventory. The normalized mean biases (NMBs) are 81 %, 21 %, 1 % and −7 % for concentrations of SO<sub>2</sub>, NO<sub>2</sub>, ozone and PM<sub>2.5</sub>, respectively, with the unit-based inventory, in contrast to 124 %, 39 %, −8 % and 9 % with the proxy-based inventory. Furthermore, the concentration gradients of PM<sub>2.5</sub>, which are defined as the ratio of urban concentration to suburban concentration, are 1.6, 2.1 and 1.5 in January and 1.3, 1.5 and 1.3 in July, for simulations with the unit-based inventory, simulations with the proxy-based inventory, and observations, respectively, in Beijing. For ozone, the corresponding gradients are 0.7, 0.5 and 0.9 in January and 0.9, 0.8 and 1.1 in July, implying that the unit-based emission inventory better reproduces the distributions of pollutant emissions between the urban and suburban areas.</p>