High accuracy and hourly-resolved emission inventories of air pollutants rely on timely updates of emission factors (EFs) and reliable temporal allocation factors, yet both remain poorly constrained for industrial point sources. In this study, we combined a dilution sampling system with online monitoring instruments to obtain 1-hour resolved mass concentrations of PM<sub>10</sub>, PM<sub>2.5</sub>, PM<sub>1</sub>, black carbon (BC), NOx, SO<sub>2</sub>, and CO emitted from five industrial sectors (cement, medicine manufacturing, glass production, textile, iron and steel) in China. Product- and fuel-based EFs were updated, as well as sector-specific hourly allocation factors optimized for air quality modeling. Their emission amounts were calculated using the revised product-based EFs and further compared with those for widely adopted Multi-resolution Emission Inventory for China (MEIC). Our measured EFs deviated from previously reported literature values by 1–4 orders of magnitude. BC EFs ranged from 3.2<span> </span>×<span> </span>10<sup><span>−</span>6</sup> to 4.7<span> </span>×<span> </span>10<sup><span>−</span>2</sup> g kg<sup><span>−</span>1</sup>, which sharply contrasts with the default zero value recommended by official technical guidelines for most industrial categories. The measured BC/PM<sub>2.5</sub> mass ratios were 0.0136 and 0.0104 for cement and iron and steel sectors, respectively, both lower than literature-reported ratios, implying substantial overestimation of industrial BC emissions in existing studies. Compared with the activity-adjusted 2024 MEIC inventory, PM<sub>2.5</sub> emissions estimated using our field-measured EFs were 29.6 and 255 times lower for cement and iron and steel, respectively, reflecting the deployment of advanced air pollution control technologies and the urgent need to update outdated EFs for industrial sources. Additionally, MEIC allocated emissions across 7,720 iron and steel grid cells, which drastically overrepresents real factory distribution. Our study adopted geolocated Point-Of-Interest data to identify only 216 actual sites, partially explaining the overestimation for industrial emissions by MEIC.</p> <p>Hourly temporal allocation factors exhibited two distinct pollutant-specific diurnal patterns: with three distinct peaks for PM<sub>10</sub>, PM<sub>2.5</sub>, and PM<sub>1</sub> within a single day and a single peak for BC, SO<sub>2</sub>, NOx, and CO. For PM<sub>2.5</sub>, normalized hourly allocation factors ranged from 0.016 to 0.055 (averaged as 0.0417 ± 0.0074).<strong> </strong>Conventional uniform temporal allocation assumptions (e.g., fixed 1/24 hourly weight) fail to capture nighttime and short-duration emission spikes, especially for particles. This work provides ground-truthed EFs and hourly allocation profiles for subcategory industrial sources, which can improve the accuracy and reliability of high-temporal-resolution emission inventories, and support the validation of industrial hourly-contribution partitioning from receptor and air quality model simulations.