Abstract: The characteristics of air pollutant transmission in Lanzhou City from January 1^st to December 31^st, 2017 were simulated and studied by using the HYSPLIT backward trajectory mode combined with air quality index (AQI) and the quality concentration data of conventional air pollutant index. The main transmission routes of air masses arriving in Lanzhou City and the characteristics of pollutant quality and concentration corresponding to each type of path were determined by cluster analyses, and the receptor model potential source contribution function (PSCF) and concentration weighted trajectory (CWT) were analyzed. This paper discusses the impact of the regional air pollution transmission on the air quality in Lanzhou City and possible potential source area. The results show that the pollution track that affects the air flow track of Lanzhou City is mostly from the west and north of Lanzhou City, and the pollution track accounts for about 39.52% of the total trajectory, indicating that the input of external pollutants has an important influence on the air quality of Lanzhou City. The air mass of the third kind of trajectory (corresponding direction to the air mass is west) has a great influence on the air quality of Lanzhou City. Although this type of trajectory only accounts for 15.21% of the total trajectory, 56.76% of the third type of trajectory belongs to the pollution trajectory, which is the main transmission path affecting the air quality of Lanzhou City. The air mass under the fourth type of trajectory (corresponding direction to the air mass is southeast) is the cleanest. The strong potential source areas that have the greatest impact on air quality in Lanzhou City are mainly distributed in Qinghai Gonghe basin, Lanzhou City and surrounding areas. The potential sources of moderate strength are the southern Inner Mongolia Autonomous Region, Ningxia Hui Autonomous Region and Gansu Hexi Corridor Areas.