Abstract: Winter is the most difficult period for the prevention and control of atmospheric PM_2.5 pollution. In recent years, Yichang City has adopted appropriate winter prevention measures for air pollution prevention and control, and achieved certain improvement results. In order to study the impact of winter control measures on air quality in Yichang City and the effect of heavy pollution emergency emission reduction during the winter control period, we analyzed the changes in air quality, particulate matter components and source resolution during the winter control period of 2019-2021 in Yichang City using the ambient air quality and component monitoring data of Yichang City, and assessed the effect of heavy pollution emergency control measures during the winter control period of 2021 during three typical heavy pollution periods. The results showed that: (1) The PM_2.5 concentration in Yichang City during the winter defense period in 2021 decreased by 4.3% compared with the winter defense periods in 2020 and 2019. (2) The concentrations of NO₃⁻, SO₄²⁻, POA and SOA decreased significantly in the 2021 winter defense period compared with the 2019 winter defense period, with the decreases of 11.8%, 12.7%, 24.4% and 29.6%, respectively. (3) During the winter defense period of 2019-2021, the main sources of PM_2.5 in Yichang City were secondary sources (35.85%-55.10%), motor vehicles (13.56%-36.08%), biomass combustion (8.26%-17.15%), industrial sources (4.34%-8.83%), and dust sources (3.78%-7.22%). The contribution of the secondary sources was high, the contribution of motor vehicles showed a decreasing trend year by year. The contribution of both secondary sources and industrial sources increased in the 2021 winter defense period compared with the 2019 winter defense period. (4) WRF-Chem model simulations showed that emergency control measures for three typical heavy pollution periods during the winter prevention period in 2021 reduced PM_2.5 concentrations by 4.2%-9.2%. The study shows that scientific winter control measures have made positive contributions to the improvement of air quality in Yichang City. However, at the same time, the compound atmospheric pollution in Yichang City has intensified, making PM_2.5 prevention and control more difficult. Precise analysis and research, and scientific pollution prevention and control will be conducive to the sustained and steady improvement of ambient air quality.