Abstract: The 72 hour backward trajectories in Huludao City from 2019 to 2021 were simulated using the hybrid single-particle Lagrangian integrated trajectory （HYSPLIT） model.Potential Source Contribution Factor Analysis （PSCF） and Concentration Weight Trajectory Analysis （CWT） based on the daily concentration data of PM_2.5 during the same period were used to investigate the potential sources in different seasons and evaluate their contributions to the concentration of PM_2.5 in Huludao City.The results showed that the main potential sources were located in Ulan Buh Desert,followed by southeast Mongolia,eastern Inner Mongolia,Beijing-TianjinHebei region and western Liaoning in winter.In autumn,the main potential sources were southern Liaoning,Beijing-Tianjin-Hebei region,northern Shandong and northern Henan.The relatively high-value sources in spring were sporadically distributed in the Beijing-Tianjin-Hebei region,Shandong and the Bohai Sea,and they were sporadically distributed in the Beijing-Tianjin-Hebei region and northwestern Shandong in summer.