The invention provides an ancient tree rejuvenating nutrient solution and a preparation method thereof, and relates to the technical field of the rejuvenation of ancient trees. The nutrient solution includes, by weight, 10-30 parts of potassium nitrate, 20-40 parts of ammonium phosphate, 5-20 parts of magnesium sulfate, 5-20 parts of zinc sulfate, 5-15 parts of copper sulphate, 4-10 parts of ammonium molybdate, 20-40 parts of potassium dihydrogen phosphate, 1-6 parts of EDTA ferric-sodium salt, 1-5 parts of boric acid, 3-12 parts of potassium iodide, 2-20 parts of indolebutyric acid, 5-15 parts of alpha-naphthalene acetic acid, 15-30 parts of radix euphorbiae lantu, 10-20 parts of common cnidium fruit, 10-20 parts of gerbera delavayi, 5-10 parts of radix Coix lacrymajobi, 5-10 parts of root of spiny raspberry, 30-80 parts of cane sugar, 0.1-0.5 part of vitamin, 2-7 parts of humic acid, and 4-8 parts of agricultural antibiotic. The preparation method of the nutrient solution is simple,and has good healing effects on problems of weak growing tendency of ancient trees, easy suffering of pest and disease hazards, slow wound healing, center of gravity deviation and unbalanced branch distribution.