Abstract: A strain of Acidithiobacillus ferrooxidans Y1 was isolated front acid mine drainage in Yunfu sulfide mine in Guangdong Procince．antd its growth rule was prelinminarily studied．The results show that negative correlation exists between the cell numbers and the ferrous concentration in culture medium along with time．which indirectly proves that Acidithiobacilluts ferrooxidans obtained energy through oxidating ferrous．When ferric iron concentration was high enough in the solution，jarosite was produced．In this process，the pH value of the solution became larger firstly and then smaller, always maintains in the range of 2．0～2．5.