Advanced exhaust after-treatment technology is required for heavy-duty diesel vehicles to achieve stringent Euro VI emission standards. Diesel particulate filter (DPF) is the most efficient system that is used to trap the particulate matter (PM), and particulate number (PN) emissions form diesel engines. The after-treatment system used in this study is catalyzed DPF (CDPF) downstream of diesel oxidation catalyst (DOC) with secondary fuel injection. Additional fuel is injected upstream of DOC to enhance exothermal heat which is needed to raise the CDPF temperature during the active regeneration process.The objective of this research is to numerically investigate soot loading and active regeneration of a CDPF on a heavy-duty diesel engine. In order to improve the active regeneration performance of CDPF, several factors are investigated in the study such as the effect of catalytic in filter wall, soot distribution form along filter wall, and soot loads. This paper also presents simulation results of temperature, pressure, and soot distribution in the CDPF.The after-treatment model is validated by comparing the simulation results with the measured data, and small deviation is obtained between the measured data and numerical results. Soot loading simulation indicates that soot accumulation is non-uniform along the CDPF, where higher soot accumulation at the end of filter monolith is observed. Moreover, the lowest soot accumulation occurs in the region near CDPF entrance. 3D contour images of regeneration simulation show that the soot oxidation rate of the filter increases when accumulated soot mass increases and temperature profile increases. Simulation results of catalyzed DPF (CDPF) reveal that additional exothermic reaction on wall improves the regeneration performance.