Based on continuous observations of black carbon (BC) mass concentration between 2018 and 2021 in Suzhou, and using the Aethalometer model and concentration weighted trajectory (CWT) analysis, this study investigates the distribution characteristics and potential source apportionment of BC in Suzhou. The results show that the mean BC mass concentration in Suzhou is 1.81 μg/m³, and it presents a decreasing trend between 2018 and 2021. Compared to that in 2018, the annual mean mass concentration in 2021 decreases by 43.6%. The analysis indicates that the combustion of fossil fuels (ff) is the largest BC source in Suzhou, 75.5% of BC is derived from BCff, and the proportion decreases year by year with the decrease of BC mass concentration. Moreover, the maximum and minimum BC mass concentration are shown in winter and summer, respectively, and both the diurnal variations of BC mass concentrations and BC_ff present a bimodal distribution. Compared to temperature and precipitation, relative humidity has less influence on BC mass concentrations; when BC mass concentration is smaller than 6 μg/m³, it decreases as the wind speed increases; meanwhile, the distribution of BC mass concentration in different wind directions does not differ greatly. The source apportionment analysis suggests that the potential source areas of BC are mostly concentrated in the southwest direction, and Zhejiang, Anhui, and Jiangxi provinces have larger influence on BC in Suzhou.