The present invention provides an erythromycin crystallizing method, which comprises using dichloromethane containing solvent as a preparation solvent, and the dichloromethane solution of erythromycin received was gradiently cooled from high temperature down to low temperature, and thus making erythromycin crystallize. According to the method of the present invention, the content of erythromycin A is high, the content of erythromycin A in the erythromycin crystalline is more than 94.5% (HPLC detection method), the content of dichloromethane in the erythromycin crystalline is less than 600 ppm, the content of water in the erythromycin crystalline is less than 2.5%, the microbiological titre of the erythromycin crystalline is more than 940 μ/mg.