A method is provided for preparing spray dried powder containing vancomycin hydrochloride. The method comprises providing a vancomycin hydrochloride solution with a chromatographic purity of at least 95%, adding an excipient to the vancomycin hydrochloride solution to form a mixture solution of the vancomycin hydrochloride solution and the excipient, concentrating the mixed solution of the vancomycin hydrochloride solution and the excipient to form a 20% to 30% vancomycin concentrate, filtering the vancomycin concentrate to form a final filtrate, and spray drying the final filtrate to form a spray dried vancomycin hydrochloride powder with EP impurity B level of not more than 1.5%.
