Abstract: The variations of peroxidase isoenzyme (POI) and enzyme activity in the root, stem and leaf tissues of Pinus armandii infected by Cinara were studied by using polyacrylamide gel.electrophoresis.The result showed that root, stem and leaf tissues infected by Cinara had higher POD activity than those of the healthy plant did, and the mumbers of band were increased.The higher the disease level the plant had, the higher the enzymatic activity and the more the band mumbers the root, stem and leaf tissues had.Comparing the healthy plant with inhealthy infected by aphid, the peroxidase enzymatic of root and stem tissues is larger than leaf tissues.