The invention discloses an antibacterial dental prosthetic material and a preparation method thereof. The antibacterial dental prosthetic material is obtained by injecting the raw materials in a specific mold for curing and forming after even mixing of 25 percent to 94 percent (by weight) of epoxy resin, 0.5 percent to 40 percent (by weight) of polyamine and guanidine oligomer, 5 percent to 65 percent (by weight) of curing agent, the amount which is equivalent to 10 to 50 percent of the total weight of the three matters of filler and the amount which is equivalent to 0 to 20 percent of the weight of the epoxy resin of epoxy thinner. The dental prosthetic material prepared by the ingredients and the method of the invention is safe for the human body, does not damage the oral bacteria groupand has the long-term antibacterial property; the antibacterial rate of the invention on staphylococcus aureus is more than 98 percent, and the antibacterial rate on Escherichia coli is more than 98 percent. The invention can be used as dental base material, adhesive, filling material, closure agent and other dental materials.