The invention discloses a preparation method of a wormwood antibacterial coating, the wormwood antibacterial coating is prepared from the following components in parts by weight: 400-600 parts of ionized water, 45-55 parts of lime, 15-26 parts of gypsum, 16-25 parts of white Portland cement, 15-20 parts of diatom ooze, 4-6 parts of folium artemisiae argyi, 3-5 parts of bentonite and 2-3 parts of cellulose, and the preparation method comprises the following steps: A, grinding and sieving ingredients; b, grinding, boiling and soaking folium artemisiae argyi; c, folium artemisiae argyi burning ash treatment; d-G, blending and stirring for 1-4 times; and H, filtering and sub-packaging. The formula is prepared from natural inorganic raw materials, folium artemisiae argyi through a traditional cooking process and folium artemisiae argyi ash through composite stirring and filtering, the smell of the folium artemisiae argyi is released for a long time, the preparation process is simple, the filtering efficiency is high, the cost is low, and the product is remarkable in sterilization effect through detection.