The problem of diesel vehicle pollution has aroused wide concern in central and southern Liaoning Urban Agglomeration (CSLA), as it is associated with large amounts of atmospheric emissions. This article focuses on heavy-duty diesel trucks (HDT) of Chinese National Standards for heavy-duty diesel trucks (GB) III, GB IV, and GB V. This research measures emission factors (EF) of NOx, CO, and PM by vehicle tests. Subsequently, the emission inventory has been established according to emission factors (EF), activity levels (AL), and Technic guidelines for road motor vehicle emission inventory of air pollutants (Guideline, 2015) in central and southern Liaoning Urban Agglomeration (CSLA). This study further obtained the spatial distribution map of pollutants in CSLA, 2019, using the Geographic Information System (GIS). Results exhibit NOx and CO emissions of HDT directly proportional to the amount of their ownership, and GB III was the main contributor to the PM emissions accounting for nearly 74%. It was concluded the annual emissions of NOx, CO, and PM in CSLA were 20.34, 6.46, and 0.044 million tons individually in 2019. Moreover, the emissions of NOx and CO in heating seasons were higher than in non-heating seasons, accounting for approximately 56% and 57% of the whole year respectively. Notably, Shenyang, Dalian, and Anshan were the top three cities in atmospheric emissions. In addition, the three kinds of pollutants mainly appeared in suburbs and decreased gradually from suburbs to urban areas.