Abstract：In this paper, the growth characteristics (the mycelium morphology and pacted mycelium volume) and fermentation medium for a strain of Streptomyces microaureus CIT-04), which produced kasugamycin, were studied. The results indicated that the hypha patterns changed greatly during the cultivation with seed medium. The best inoculate time was 33h when the seed mycelial concentration was 25% PMV. The optimization of the medium was carried out by using the orthogonal analytical method, and the optimum medium components was: soybean cake powder (4%), edible soybean oil (2.5%), KH2PO4 (0.05%), corn starch (0.1%), NaCl (0.5%), peptone (0.5%), maltose (3%), silkworm chrysalis powder (1%), and MgSO4 (0.03%). Under the optimized condition, the titer of kasugamycin produced by CIT-04 was up to 18780U/mL.