The invention discloses an antibacterial automobile air conditioner shell and a preparation method thereof. The method comprises the following steps: 1) carrying out activation treatment on bentonite and shell calcinate in the presence of X-ray to obtain an activating agent; 2) mixing PC (polycarbonate), PF (phenol-formaldehyde resin), PAN (polyacrylonitrile), nano aluminum oxide, talcum powder, diethyl malonate, pentaerythritol, glass fibers, potassium chloroplatinate, zirconium phosphate, antimony pentaoxide, N-phenyl maleic amide, dibasic lead phosphite, barium stearate and dicumyl peroxide with the activating agent to obtain a mixture; and 3) curing the mixture, thus preparing the antibacterial automobile air conditioner shell. The antibacterial automobile air conditioner shell prepared by the method not only has excellent mechanical properties but also has excellent antibacterial property. The preparation method is simple in steps and raw materials are easy to obtain.