12 Kinds of fishiries druges were tested to see the sonsitirity of the strain of hemorrhagic septicemia in Mugil So-iuy Basilewsky. The results showed that the efficiency of some kinds, such as norfloxacin, chloramphenicol and MZ+TMP. Were much stronger than those of others, the efficienty rates that 15-25 mg/kg and 20-30 mg/kg of norfloxacin separately prerented and controled the hemorrhagic septicemia in Mugic So-iuy, Basilewsky. Were all more than 80%, Norfloxacin's LD50 was 514.6 mg/kg in Mugil So-iuy, Basilewsky. The micronucleus test showed that norfloxacin didn't sharply cause the micronucleus rate of red celles. The efficienty rate of norfloxacin's controlling this disease was 89.5% and higher 42% on the testing pond than that of the control group of 47.5%