The mutation breeding of high-yield oxytetracycline-producing strains and the optimization of their ferment conditions were studied. seven mutagenic methods, including UV-induced mutation, licl-induced mutation, microwave irradiation, ion implantation of NaNO₂, NTG, NaN₃and N⁺, were tested on streptomyces rimosus 186^#, and the mutagenic effects were statistically analyzed from lethallty rate, morphological variation rate, positive mutation rate and mutation extent. The results showed that all of the 7 strategies were effective, in which licl, microwave, NaNO₂and NTG were easy-operated and less time-consuming with high positive mutation rate, large mutation extent and good mutation effects.