|This study was carried out to investigate the low emission of air pollutants from diesel vehicle equipped with DPF, p-DPF and DOC attachment in Suwon city. The reduction quantity of particle matters(PM) by DPF, p-DPF and DOC attachment was 12.5ton/yr., 1.4ton/yr., and 0.03ton/yr. respectively. In the case of hydorgen carbon(HC), the reduction quantity was estimated 20.6ton/yr. by DPF attachment, 5.4ton/yr. by p-DPF attachment and 0.08ton/yr. by DOC attachment. In the case of CO, the reduction quantity was in the order of DPF(74.7ton/yr.) ＞ p-DPF(15.7ton/yr.) ＞ DOC(0.8ton/yr.). The observed results demonstrate that low emission from diesel vehicles can be achieved by appplying reduction systems such as DPF, p-DPF, and DOC, which of contributions to air quality were verified in terms of PM, HC, and CO.