Oxidation is the main cause for road asphalt aging.Asphalt aging contributes to a decrease in penetration and deterioration in pavement performance.Asphalt aging yields a lot of polar carbonyl group.Infrared spectrum of original and aged asphalt samples was investigated,and the absorbance ratio of different degree of aging was calculated.According to penetration changes of aged asphalt,there is a direct correlation between penetration and infrared spectrum absorbance changes.A relationship between pavement performance and asphalt chemical composition is established.The result is of value to analyse asphalt oxidation mechanism.