Abstract: During the period from April 11 to April 25, 2022, the chemical composition and source of fine particles in Jinggu County urban area in spring were analysed by using the single particle aerosol mass spectrometer（SPAMS）, and the pollution characteristics of fine particles in this area were studied in combination with the PM_2.5mass concentration monitored by the County Air Automatic Station. The results showed that the main components of fine particles in Jinggu County in spring were potassium ion, sulfate, elemental carbon, nitrate, organic carbon and chloride ion. The main pollution sources were coal-fired sources, vehicle tail gas sources and industrial process sources. Five short-term pollution weather periods were captured during the monitoring period, at which time the coal-fired source was often the main pollution source; The peak value of the proportion of coal-fired sources mostly occurred from 14:00 to 16:00, the proportion of Vehicle Exhaust Sources in the daytime was higher than that at night, and the peak value of industrial process sources mostly occurred from 21:00 to 9:00 the next day. The proportion of industrial process sources, biomass combustion sources and secondary inorganic sources in the urban area of Jinggu County increased with the increase of PM_2.5 mass concentration; the proportion of catering sources increased with the decrease of PM_2.5 mass concentration.