The present invention relates to levocarrimycin, its pharmaceutical compositions, preparation methods and application. Levocarrimycin is a mixture of isovalerylspiramycin III, II and I as main components and contains some isobutyrylspiramycin III and II, butyrylspiramycin III and II, propionylspiramycin III and II, as well as acetylspiramycin III and II, among which, the content of isovalerylspiramycin III is no less than 30 wt %, the total content of isovalerylspiramycin III, II and I is no less than 60 wt %, and the content of acylspiramycin is 80-98 wt %. Specific optical rotation of said levocarrimycin is [α]D=−52°˜−57° in the solution of 0.02 g/ml chloroform at temperature of 25° C. The present invention also relates to the crystalline compound of isovalerylspiramycin III, II or I in levocarrimycin, and pharmaceutical compositions containing the said levocarrimycin. In present invention, the active components in levocarrimycin or its pharmaceutical compositions have optical activity and excellent anti-infective effect.
