The invention belongs to preparation of antibiotic, in particular to preparation method of Valnemulin and hydrochloride thereof.D-hydroxy valine Dane salt is added into more than ten weight of tetrahydrofuran and is suspended by stirring at 0-20 DEG C, and triethylamine, N, N-dimethyl formamide (acetamide) and N-methyl morpholine are added until reaction liquid is clear; methyl (ethyl) chloroformate molar weight of which is not more than that of D-hydroxy valine Dane salt is added; (2-amino-1, 1-dimethyl ethyl) mercaptoacetic acid, (3aS, 4R, 5S, 6S, 8R, 9R, 9aR, 10R)-octohydrogen-5, 8-dyhydroxy-4, 6, 9,10-tetramethyl-6-ethenyl-3a, 9-propane-3aH-cyclopentene (cyclooctene)-1(4H)-keto-8-ester the molar weight of which is not more than that of D-hydroxy valine Dane salt is dissolved in equal mass of tetrahydrofuran, the reaction liquid is dripped in and stirred at 0-10 DEG C, and reaction is carried out for 2-5h at 0-20 DEG C; the organic solvent is removed, the residue is added with water and hydrochloric acid is used for adjusting pH value, heating up, stirring and decontaminating are carried out, and the filtration is freeze dried to obtain Valnemulin hydrochloride. The invention solves the problems of low purity and high reaction condition of the existing product and has the advantages of simple technology and high product purity.