Diesel burners have been used to regenerate diesel particulate filters (DPF) because of their simplicity in engine torque control and less oil dilution by fuel compared with the commonly used in-cylinder post fuel injection method. We previously developed a novel diesel burner using rotating plasma as an ignition source and found it to be effective in DPF regeneration. Here, we carry out in-depth studies on combustion efficiency of this plasma-ignited diesel burner and investigate the effects of influential factors such as plasma power, the amount of fresh air supplied, and O2 concentration in the exhaust gas on combustion characteristics of the burner. The obtained results show that fresh air supplied to the burner plays an important role in ignition and the early stage of combustion, and O2 concentration in the exhaust gas is identified as the most dominant factor for combustion efficiency. However, the results also indicate that plasma power and exhaust gas flow rates are insignificant in burner performance. Additionally, it is found that HC and CO emitted from the burner during DPF regeneration can effectively be suppressed with the DOC (Diesel Oxidation Catalyst). The PGM amount and volume of DOC should be determined to respond to even the case where the burner has the lowest possible combustion efficiency.