China has produced roughly half of the world’s steel in recent years, but the country’s iron and steel industry is a major source of air pollutants, especially particulate matter, SO₂ and NO_x emissions. To reduce such emissions, China imposed new emission standards in 2015 and promoted ultralow emission standards in 2019. Here we use measurements from China’s continuous emissions monitoring systems (covering 69–91% of national iron and steel production) to develop hourly, facility-level emissions estimates for China’s iron and steel industry. In turn, we use this data to evaluate the emission reductions related to China’s increasingly stringent policies. We find steady declines in emission concentrations at iron- and steelmaking plants since the 2015 standards were implemented. From 2014 to 2018, particulate matter and SO₂ emissions fell by 47% and 42%, respectively, and NO_x increased by 3%, even as the production increased by 14%. Moreover, we estimate that if all facilities achieve the ultralow emission standards, particulate matter, SO₂ and NO_x emissions will drop by a further 50%, 37% and 58%, respectively. Our results thus reveal the substantial benefits of the Chinese government’s interventions to curb emissions from iron and steel production and emphasize the promise of ongoing ultralow emission renovations.