Although diesel engines have higher output torque, lower fuel consumption, and lower HC pollutant emissions, larger amounts of NOx and PM are emitted, compared with equivalent gasoline engines. The diesel particulate filters (DPF) have proved one of the most promising aftertreatment technologies due to the more stringent particulate matters (PM) regulations. In this study, the computational fluid dynamics (CFD) model of DPF was built by utilizing AVL-FIRE software code. The main objective of this paper was to investigate the pressure drop and soot regeneration characteristics of hexagonal and conventional square cell DPFs with various inlet mass flow rates, inlet temperatures, cell densities, soot loads and ash loads. Different cell geometry shapes of DPF were evaluated under various ash distribution types. Results showed that, in comparison with the conventional square cell DPF, a remarkable increase of regeneration efficiency and soot oxidation rate of hexagonal cell DPF is confirmed. The optimal cell density range is (220-260)/ inch2. The ash deposited on inlet channel walls results in larger pressure drop and prevents soot accumulation in the pores dramatically compared with ash deposited as plug. In addition, the hexagonal cell DPF has a lower pressure drop than square cell DPF at high soot and ash loads. In a word, the hexagonal cell DPF exhibits a better performance of soot capacity and soot regeneration than square cell filter, which reduces the regeneration frequency and prolongs the DPF life.