The invention relates to an antibacterial soap and a preparation method thereof. The antibacterial soap is prepared from the following raw materials: sodium palmitate, sodium myristate, sodium laurate, fatty alcohol-polyoxyethylene ether-sodium sulfate, plant essential oil, sugar ester, glycerin, sodium chloride, pullulan, 2,6-di-tert-butyl-4-methyl phenol, disodium ethylene diamine tetraacetic acid, essence, pigments, antiseptic, and the balance being deionized water; wherein the plant essential oil is a mixture of essential oil of folium artemisiae argyi and essential oil of tea tree; and the sugar ester is a mixture of glucose octenyl succinate and starch sugar octadecenyl succinate. The provided antibacterial soap is safe, nontoxic, and barely irritant, has the functions of preventing bacteria and allergy and eliminating inflammation, can clean the skin, retain the water in skin, and nourish the skin, and is suitable for long term use.