The invention discloses a preparation method of a nutrient for promoting growth of a medicinal whole-grass plant. The nutrient comprises, by weight, 10 to 30% of a nucleotide salt, 20 to 70% of glucose, 10 to 21% of amino acids and 10 to 30% of a medium trace element, wherein the medium trace element is Mn, B, Fe, Zn, Cu or Mo. The nucleotide salt, the amino acids and the medium trace element are crushed and screened and the glucose is added into the mixed powder and the mixture is uniform mixed. The preparation method has a low cost and a small use amount, has simple processes and is suitable for large-scale production and popularization. The nutrient has a reasonable ratio of all the ingredients, strong pertinence, no toxicity, no damage, no residual and no side effects, has effects of improving a yield, income, effects and resistance, can promote growth of a medicinal whole-grass plant and can improve a yield by 40-100%.