Abstract: A high spiramycin yielding and phage resisting mutant was obtained by way of mutagenesis. The starting strain Streptomycin spiramyceticus PS was first treated with Co irradiation, the phage resisting mutant R10 isolated with a slightly higher yield. Then from strain R10 through rational screening, the strain T 8 was isolated on a plating medium, containing 2 deoxy glucose. T 8 has the stable phage resisting feature with a 20% increase in yield and 12h shortening in fermentation time when cultivated in shaking flask as compared with R10.