Application of Non-thermal plasma for gas cleaning is gaining prominence in recent years, which can effectively remove NOx and other exhaust gases simultaneously. As the present researches are mostly adopting simulation gas for the investigation, this paper employed the NOx from the actual diesel exhaust as the investigated subject. Effects of the amplitude and frequency of voltage, the diameter of high-voltage electrode, the reactor volume and the discharge gap on NOx removal were studied based on dielectric barrier discharge. Obtained results indicate that, the removal rate of NOx increased first and then decreased with increasing the magnitude and frequency of the voltage. With decreasing discharge gap, the removal rate of NOx increased. With increasing the volume of reactor and the diameter of high-voltage electrode, the removal rate of NOx increased.