Abstract: Open biomass burning is one of the important sources of particulate matter (PM) and gaseous species at the global scale, whereas crop residual burning is the fundamental way of biomass burning in East China. By using surface observations of air quality and meteorological variables, aerosol optical depth (AOD) data from Aerosol Robotic Network (AERONET), biomass burning emission from Global Fire Emissions Database (GFED) inventory, and the Weather Research and Forecasting model with Chemistry (WRF-Chem), this study investigated the evolution of air pollutants in the Huabei Plain in October 2014, focusing on a severe haze event in Beijing in 7-11 October. The synoptic condition, boundary layer meteorology, transport pathway, spatial-temporal distribution of aerosol chemical components in PM2.5, and the impact of crop residual burning on fine particle concentration and surface shortwave radiation during this period were analyzed. The model well reproduces the surface meteorological variables and PM2.5 concentrations but underpredicts the AOD and overpredicts the surface shortwave radiation during haze days. Notably, the model simulation of PM2.5 concentration substantially improved by considering crop residual burning emission. The severe haze event in 7-11 October in Beijing was mainly caused by the accumulation and regional transport of air pollutants under stable atmospheric condition and was also affected by the northward transport of air pollutants produced by crop residual fires over the wide areas of southern Hebei, northern Henan, and western Shandong province. The model simulation revealed a considerable influence of crop fire on the surface aerosols in Beijing, with the percentage contributions of 24.6%, 36.8%, 23.2%, 22.6%, 7.1%, and 19.8% for PM2.5, organic carbon (OC), nitrate, ammonium, sulfate, and black carbon (BC) concentrations, respectively. The mean reduction in the surface shortwave radiation in Beijing induced by aerosols from crop fire exceeded 20 W m⁻², accounting for approximately 24% of the changes in shortwave radiation by all aerosols.