Air　pollution　during　the　COVID-19　epidemic　in　Beijing　and　its　surrounding　regions　has　received　substantial　attention.　We　collected　observational　data,　including　air　pollutant　concentrations　and　meteorological　parameters,　during　January　and　February　from　2018　to　2021.　A　statistical　and　a　numerical　model　were　applied　to　identify　the　formation　of　air　pollution　and　the　impact　of　emission　reduction　on　air　quality.　Relative　humidity,　wind　speed,　SO2,　NO2,　and　O(3　)had　nonlinear　effects　on　the　PM2.5　concentration　in　Beijing,　among　which　the　effects　of　relative　humidity,　NO2,　and　O-3　were　prominent.　During　the　2020　epidemic　period,　high　pollution　concentrations　were　closely　related　to　adverse　meteorological　conditions,　with　different　parameters　having　different　effects　on　the　three　pollution　processes.　In　general,　the　unexpected　reduction　of　anthropogenic　emissions　reduced　the　PM2.5　concentration,　but　led　to　an　increase　in　the　O-3　concentration.　Multi-scenario　simulation　results　showed　that　anthropogenic　emission　reduction　could　reduce　the　average　PM2.5　concentration　after　the　Chinese　Spring　Festival,　but　improvement　during　days　with　heavy　pollution　was　limited.　Considering　that　O-3　enhances　the　PM2.5　levels,　to　achieve　the　collaborative　improvement　of　PM2.5　and　O3　concentrations,　further　research　should　explore　the　collaborative　emission　reduction　scheme　with　VOCs　and　NO(x　)to　achieve　the　collaborative　improvement　of　PM(2.5　)and　O-3　concentrations.　The　conclusions　of　this　study　provide　a　basis　for　designing　a　plan　that　guarantees　improved　air　quality　for　the　2022　Winter　Olympics　and　other　international　major　events　in　Beijing.