The invention relates to an antibacterial PC/ABS alloy material and a preparation method thereof. The antibacterial PC/ABS alloy material includes the following components, by weight: 40-80 parts of PC resin, 20-60 parts of ABS resin, 5-20 parts of bamboo powder and 1-3 parts of a compatilizer. The preparation method includes the following steps: 1) weighting the ABS resin, the bamboo powder and the compatilizer and feeding the components into an internal-mixing and extruding machine to perform mixing granulation to obtain a first mixture; 2) mixing the first mixture with the PC resin uniformly and feeding the mixture into a double-screw extruder to perform blending granulation to prepare the target product. Compared with a material in the prior art, the alloy material is good in antibacterial performance, is excellent in mechanical performance, is simple in preparation process and is prepared from easy-to-obtain raw materials.