The nature of bacterium which can produce oxytetracycline was improved.The bacteria were treated with UV rays (UV), and then cultured (for selecting) on the medium with 2-deoxy-D-arabino-nexose.The optimum time of UV treatment for mutation breeding was 30 s.Based on that result, we got a higher production bacterium, numbered 9-15#, and its yield was 13.0% at shake flask culture and 6.1% at production condition than its origin.Treated with UV and selected on medium with 2-deoxy-D-arabino-nexose the higher oxytetracycline yield of Streptomyces rimosus can be achieved.