Eco-toxicological effects of germanium on activities of catalase,dehydrogenase,urease,phosphatase and invertase in brown-yellow soil were studied by means of indoor culture and pot culture experiments.The results showed that when Ge concentration ranged between 2~200 mg kg^-1 in the soil,its inhibiting effect on soil dehydrogenase,phosphatase and invertase was not significant,but quite so the activity of soil catalase and urease;especially the latter.A significant negative relationship between urease activity and Ge concentration of soil could be observed,so it is feasible to use inhibition rate of soil urease as a bio-indicator for ecological risk assessment of Ge pollution in the soil.