Powdery mildew caused by Erysiphe quercicola is one of the major diseases of rubber trees. There have been large outbreaks in rubber tree planting areas in China in recent years, seriously reducing the rubber yield. As a common protective forest species in rubber plantations, the evergreen tree Acacia mangium is one of the important host of rubber tree powdery mildew. The study of the biological interactions between E. quercicola and A. mangium could improve the understanding of the behavior of E. quercicola and provide technical guidance for effectively controlling of the primary source of the disease. In this study, cold acclimation significantly enhanced the resistance of A. mangium to rubber tree powdery mildew. The young leaves of A. mangium cultured at 23 ℃ had severe lesions when inoculated with E. quercicola, the young leaves of plants acclimated at 19 ℃ for 30 days had less lesions, and the young leaves of plants acclimated at 15 ℃ for 30 days and the mature leaves cultured at 23 ℃ had no lesion. Electron microscopy scans revealed that the surface of young leaves of A. mangium cultured at 23 ℃ was uneven. The surface of the young leaves cultured at 19 ℃ tended to be flat, with a raised and well-arranged waxy crystal structure. The raised and irregularly waxy crystal structure superimposed and entangled with each other. The surface of young leaves of plants acclimated at 15 ℃ and mature leaves of plants cultivated at 23 ℃ was flat. The surface of the waxy crystal structure was smooth and had obvious crystal-like waxes. Gas chromatography-mass spectrometer (GC-MS/MS) was used to analyze the wax content of A. mangium leaves on both the qualitative and quantitative level. Compared with the young leaves of A. mangium cultivated at 23 ℃, the wax composition of the young leaves acclimated at 15 ℃ and 19 ℃ and the mature leaves of the plants cultured at 23 ℃ were more complex. The main wax components and contents of young leaves acclimated at 15 ℃ were more consistent with those of mature leaves cultured at 23 ℃, and the relative contents of C₃₆ alkane, C₃0 ketone, C₃₂ ester, and C₃₀ alcohol were significantly decreased. In addition, cold acclimation at 15 ℃ could increase the SOD, CAT and POD oxidase activities of young leaves of A. mangium infected by E. quercicola, with SOD enzyme showing the greatest increase. In summary, cold acclimation may improve plant disease resistance by promoting the maturation of the structure and composition of the waxes of young leaves of Acacia mangium and restraining the infection of E. quercicola. This study is useful for understanding the interactions between rubber tree powdery mildew and its hosts, and provides a theoretical basis for efficient control of this disease.