The invention belongs to the field of food preservatives, and relates to a preparation method of a lacquer wax composite nanometer silver liquid antibacterial coating preservative. A lacquer wax silver emulsion is prepared from refined lacquer wax, and a gingko lipoid nanometer silver emulsion is prepared through sub-critical extraction of ginkgo leaves and a saponification reaction. Through the comparison of the stability and antibacterial and bacteriostatic properties, a compounding process of the lacquer wax silver emulsion, the gingko lipoid nanometer silver emulsion and a lac emulsion isdetermined, the lacquer wax composite nanometer silver liquid antibacterial coating preservative is prepared, the coating treatment has an antibacterial effect on staphylococcus aureus, bacillus subtilis and other fungi, the performance of the preservative is superior to the effect of single coating of lac on the rot of mandarin oranges, the rotting rate of the oranges is greatly reduced, and thefresh-keeping effect is good.