Abstract: Golden apple snail (Pomacea canaliculata) is one of the 16 most harmful exotic species in China. Due to its strong adaptability, omnivorous habit and high ability of reproduction, it has made serious damage to aquatic ecosystems like paddy fields. A laboratory experiment was conducted to examine impacts of golden apple snail (GAS) on water environment and influence of GAS excretion on the growth of yeast and actinomycete. The main experimental results showed that the culture solution of GAS appeared to be weak acid, while that of the control was weak alkaline. The turbidity, contents of total P and total N increased significantly as the culture time elapsed. Moreover, the culture solution of GAS resulted in significant increase in both amounts of yeast and total microbes, but there were no significant differences for either yeast or actinomycete among the treatments of different GAS densities. This study indicates that golden apple snail invasion would probably cause environmental problems of water eutrophication and quality deterioration. These findings may be helpful for assessing the ecological risk of GAS invasion.