17β-estradiol(E2) has estrogenic activity at very low concentrations and are emerging as a major concern for water quality. Great endeavors have been done on the removal of E2 in wastewater. This article was mainly researched the isolated of E2 degradation bacteria from activated sludge and its degradation characteristics of the bacteria were also researched. According to its physiological biochemical results analysis, this strain was identified as K.pnem. pneumoniae .This strain can use E2 as sole carbon and energy source for growth. The optimal temperature, pH for the bacterial growth and degradation of E2 was 30°C,7.0, respectively, meanwhile degradation rate reached to 86% and 87%; degradation rate and bacterial growth increased along with E2 concentration increasing, 81% E2 was degraded when E2 concentration is 30mg/L, degradation rate decreased when E2>50mg/L; metal ions such as Fe2+ and Zn2+ almost have no effect on E2 degradation and bacterial growth; Mn 2+ can promote growth of strain and degradation, while, metal ions such as Hg2+ ,Ag+ ,Cu 2+ have negative effect on bacterial growth and degradation. The degradation process for E2 with initial concentration of 1mg/L indicated that the degradation rate of E2 by strain within 7days was 98%.