The influence of ethylene glycol (EG) addition on pore self-ordering process in anodic aluminum oxide (AAO) membranes prepared by hard anodization (HA) was investigated. It was illustrated that EG has a substantial effect on the pore arrangement of AAO, which revealed that a smaller pore size can be obtained as EG concentration reaching 20 wt% in aqueous electrolyte. The number of estimated defects of AAO increase significantly with additive EG concentration at 50 wt%. Excellent ordering pore was realized when the samples were anodized in the 30 wt%-EG-containing aqueous electrolyte.electrolyte. The number of estimated defects of AAO increases significantly upon the added EG concentration reaching 50wt%. Excellent ordering pore was achieved when the samples were anodized in a 30wt%-EG-containing aqueous electrolyte.