Synthesis method of tiamulin

The invention relates to a synthesis method of tiamulin. Especially, the method includes: under the catalysis of a sodium hydroxide or potassium hydroxide aqueous solution with an equal mole to a raw material and has a concentration of 15-20%, p-toluene sulfonic acid pleuromutilin ester and equimolar 2-diethylaminoethyl mercaptide react for 60-70min in a methyl isoamyl ketone solvent at 50-60DEG C so as to obtain a tiamulin reaction liquid. High pressure liquid chromatograph analysis shows that the chromatographic purity of the tiamulin reaches 94.5-95.1%.