The invention discloses a preparation method of a liquid culture medium suitable for tender stems of dendrobium officinale. The preparation method comprises the following steps of adding coconut juice, a potato extract, an apple extract and other materials into 5 to 7 times of water under room temperature, and uniformly mixing to obtain a product A; pre-dissolving 2,4-D and NAA (naphthylacetic acid) by anhydrous ethanol, and preparing into a solution with concentration of 0.5 to 1.5 mg/ml to obtain a product B; and loading the product A and the product B into a tissue culture bottle, uniformlymixing, sterilizing for 20 to 30 min by steam at high temperature, and cooling to obtain the liquid culture medium. The liquid culture medium disclosed by the invention has the beneficial effects that by adding and controlling the concentrations of the coconut juice, the apple extract and the potato extract, the contents of polysaccharide and extracts in the tender stems of the dendrobium officinale are increased.