Belonging to the technical field of boar semen dilution, the invention relates to a boar antiviral long-acting semen diluent formula and a preparation method. The boar semen diluent comprises: alpha-D-glucopyranose powder, fructose, trisodium citrate dihydrate, ethylenediamine tetraacetic acid disodium, sodium bicarbonate, polyvinyl alcohol, trishydroxymethylaminomethane, inositol, vitamin C, arginine, a radix isatidis injection, a 5% ceftiofur sodium injection, and a 5% Ribavirin injection. The preparation method includes: dissolving all the components in distilled water, mixing the components evenly, and conducting sterilization to obtain the boar semen diluents. The formula involves rich nutrients, antibacterial Chinese and western medicine components and antibacterial components, thus ensuring normal sperm metabolism. After certain period of time at the lower limit of storage temperature, the effects of nutrition and sperm shock prevention can be realized, and the invasion of external bacterial viruses in an artificial insemination process can be avoided.