Atmospheric visibility is closely correlated to atmospheric extinction, which is directly affected by water vapour and the presence of aerosols. To quantitatively analyse the effect of chemical composition and size distribution of aerosols on the scattering coefficients, atmospheric samples were collected at Xianghe Station, North China Plain, in December 2018. The concentration of non-refractory chemical components, measured via high-resolution time-of-flight aerosol mass spectrometry, was the highest in the ‘Low visibility stage (L1)’, with an average value of 77.7 μg m−3, wherein the mass concentration of organic matter accounted for 36.5%, and that of three secondary inorganic aerosols accounted for 57.4%. The scattering coefficients measured using the nephelometer and those calculated based on organic matter, sulphate, nitrate, and ammonium were largely the same, and the Pearson correlation was up to 0.82. A single-particle aerosol mass spectrometer was used to measure the vacuum aerodynamic diameter and chemical composition of a single particle. The extinction contribution proportions of combustion sources and biomass burning sources were 45.0% and 36.4%, which decreased by 3.2% and 4.9%, respectively, compared with the number concentration proportion of these sources (46.5% and 38.3%, respectively); this is related to the fact that the composition of these sources, contained more optically absorbent substances, will cause a drop in the scattering coefficients. Therefore, we further analyzed the source apportionment of aerosol optical scattering based on its composition and particle size distribution, which was able to provide guidance for controlling which pollutant emission will reduce the optical scattering value of aerosol during low visibility.