Abstract: At the end of November 2018, Zibo City experienced a heavy atmospheric pollution episode caused by the influence of sand and dust. In order to study the formation mechanism of the particulate matters during the heavy pollution, the concentrations of PM₁₀ and PM_2.5 and the chemical composition of PM_2.5 were analyzed. The source of particulate matter was studied using the PMF model and the backward trajectory model. The results showed that: (1) During the pollution period, the average concentrations of PM₁₀ and PM_2.5 were (259±111) and (133±51)μg/m³, respectively, which were 2.9 and 3.7 times higher than the period after pollution. (2) Affected by sand and dust, Ca²⁺, Mg²⁺, Al, Mg, Ca, Si, etc. represented the ion and element components of sand and dust sources, and their mass concentrations in PM_2.5 were higher than that after pollution. (3) The 72 h backward trajectory showed that the accumulation of pollutants was attributed to the locally circling air mass and the long-range dust transportation from the northwest. The air pollution process was the combined result of pollutant accumulation and northwest dust transportation. (4) The PMF results showed that the dust source was the primary source and contributed to 33.61% of PM_2.5 during the pollution period, indicating that sand dust played an important role in this pollution process. After the pollution process, the contribution of industrial sources increased significantly, accounting for 22.71% of the pollution, reflecting the characteristics of Zibo City as a heavy industry city. The results indicate that the source of particle in the heavy pollution period in Zibo City is complex, which is not only affected by the local regional pollution, but also greatly affected by dust migration.