To improve the effect of plasma on the surface modification of polymer materials and optimize the hydrophilic treatment conditions, the hydrophilic modification of polypropylene (PP) by AC and nanosecond pulse argon dielectric barrier discharge (DBD) was studied. The discharge characteristics of AC DBD and nanosecond pulse DBD were systematically compared by using electrical and optical diagnostic.The results show that the DBD excited by nanosecond power supply has higher instantaneous discharge power, better discharge uniformity and higher energy efficiency. The optimal content of H₂O in hydrophilic treatment of PP was determined by measuring the intensity of OH. The hydrophilic modification of PP was carried out by using DBD driven by AC and nanosecond pulse power supply, respectively. The water contact angle of PP was measured under different conditions. The surface physical morphology and chemical composition of PP were analyzed by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR).The result shows that, after DBD treatment, the water contact angle of PP surface was obviously reduced, the surface roughness increased significantly, and the number of hydrophilic oxygen-containing groups, hydroxyl (-OH) and carbonyl groups (C=O), increased significantly. Compared with the AC power supply treatment, the modification effect of nanosecond pulse DBD treatment is obviously better, by which the water contact angle of the treated material surface is about 5° lower and the surface roughness is larger. In addition, the water contact angle of PP was further reduced about 4° and the surface roughness was significantly improved with the addition of water vapor. The results have significant value for optimizing the experimental conditions and treatment effect of surface modification of DBD polymer materials.