The cholesterol oxidase producing strain Brevibacterium sp. DGCDC-82 was treated with NTG (1 mg/mL) under ultrasonicztion(200 W, 50 kHz). A red mutant named Brevibacterium sp. DGCCN-25 showed higher and stable production of cholesterol oxidase was obtained. The enzyme activity was increased by 140%, it is 1.24 U/mL.Then dealed with DGCCN-25 using the same method, two revertants were obtained, one was white and the other was rose pink. The enzyme activity of two revertants was obvious decrease, they are 0.17 U/mL and 0.69 U/mL.The results showed the positive correlation between COD acticity and red pigment producing by Brevibacterium sp.. The relativity model can be used as a method of screening for mutation and directed evolution.