Abstract: In this paper,the on-board diagnostic （OBD） remote emission monitoring data of Stage VI heavyduty vehicles （HDV）collected by the HDV OBD system in Chengdu in December of 2023 were used as the object of analysis to screen vehicles with excessive NO_x emissions.The results showed that 826 NO_x-exceeding vehicles were detected during the statistical cycle,accounting for 9.93% of the total number of vehicles;the total amount of NO_x emissions of the exceeding vehicles were 2735.57 kg,with an average daily emission of 88.24 kg.This study generated a heat map of the activities of excessive vehicles,compiled a detailed list of HDV with excessive emissions,and matched the list of excessive vehicles with the existing annual inspection database of Chengdu,which could be further compared horizontally with the data of remote sensing detection,roadside inspection,field inspection,and other regulatory operations.This study could provide data support for the supervision of HDV emissions in Chengdu,and help to further promote the precise pollution prevention and control of mobile sources in Chengdu.