Diesel oxidation catalyst was installed in front of diesel particulate filter. The engine exhaust temperature was improved by insufflating diesel oil into vent-pipe upriver diesel oxidation catalyst. The engine exhaust flow was reduced to further improve the exhaust gas temperature and achieve the regeneration of diesel particulate filter. The system was consisted of fuel injector, diesel oxidation catalyst and diesel particulate filters. Study on regeneration characteristics of this system on engine test-bed, including the temperature characteristics of the diesel oxidation catalyst in regeneration, the relationship of injection flow rate and temperature, DPF regeneration process and the fuel economy and secondary pollution of regeneration. The results demonstrates that DOC assisted DPF regeneration can be successfully achieved under idle condition, diesel oil consumption under regeneration process is 120.5g, emissions of CO and HC under regeneration process are 12.4g and 1.1g, respectively.