The invention relates to a preparation method of an acetobacter xylinum culture solution. The preparation method comprises: (1) stock culture of acetobacter xylinum: inoculating acetobacter xylinum mycelia to a bevel culture medium, transferring the acetobacter xylinum mycelia to an incubator to be cultured for 4-5 days till bacterial colonies grow, and transferring the acetobacter xylinum myceliato a 5 DEG C refrigerator; (2) acetobacter xylinum mycelia seed solution culture: inoculating the acetobacter xylinum on the bevel culture medium to a seed culture solution in a proportion of 1% (m/v), transferring the same into an oscillating incubator for shake cultivation for 4-5 days at 160 r/min at 30 DEG C till an obvious layering phenomenon appears and the solution is covered with a shallow white film, and transferring the seed solution into the 5 DEG C refrigerator; and (3) acetobacter xylinum fermentation solution culture: inoculating the acetobacter xylinum of the seed culture solution to a fermentation culture medium in a proportion of 7% (v/v), transferring the same into biochemical constant temperature incubator to be cultured stationarily for 15-20 days at 30 DEG C till theliquid level is covered by a shallow white film which is visible. The coating fresh keeping method adopting the culture method comprises the following steps: adding a biological coating agent into a 1-3% surfactant, and diluting the same with sterilize water for 50-200 times; and putting fruits and vegetables in a culture solution for 0.5-1 min and taking out the fruits and vegetables out, airingthe same, and packaging the same with fresh-keeping bags.