Abstract: An indoor inoculation experiment was conducted to determine acetochlor effect on soil microbe and enzyme activity. The results indicate that numbers of bacteria and actinomycete increase two weeks after applying acetochlor, then inhibited by 30 mg·kg^-1 acetochlor at the 30th day. After that, actinomycete number recovers while bacteria number is still inhibited till the 60th days. Fungi number decreases at 14 days after applying acteochlor, but then recovers at the 30th day and is stimulated at the 60th day. Soil dehydrogenase activity is stimulated two weeks after applying acetochlor, then is inhibited by 30 mg·kg^-1 acetochlor from 45 to 60 days after application. Catalase activity is not sensitive to acetochlor, but invertase and urease are sensitive at the early period of application. Invertase activity is inhibited by 0.3 mg·kg^-1 acetochlor, but stimulated by 3 mg·kg^-1 and 30 mg·kg^-1 acetochlor. Urease activity is inhibited by acetochlor in different application amount.