Abstract: Superoxide dismutase( SOD) activity in different parts of Pleurotus eryngii was compared.Several factors affecting the stability of SOD including p H,temperature,metal ions and organic reagents,were studied.The results showed that SOD enzyme activities in pileus and gill were higher than that in stipe,the skin higher than core section.This enzyme displayed good stability at the p H range from 5 to 8 and good thermal stability. Cu~(2+),Zn~(2+),Fe~(2+) and Mn~(2+) showed different degrees of activation on SOD enzyme activity,in which the activation of Cu~(2+) was the most prominent. Methanol,ethanol and n- butyl alcohol showed activation in low concentration but inhibitory effect in high concentration,while acetone showed inhibitory effect.Therefore SOD activity of Pleurotus eryngii were influenced by many factors including p H,temperature,metal ions and organic solvents.