Abstract: This paper reports the result of the characteristies of 21 of the 23 strains of acid-fast bacilli studied by means of Kubica's 12 differential identification tests for mycobacteria.These 21 strains could be divided into Group Ⅰ including 14 strains,Group Ⅱ including 4 strains,and 3 remaining straias of questioaable position.