The potential effect of 1,4-dichlorobenzene(1,4-DCB) on Microbial Populations and enzyme activities was investigated in a flooded wetland soil. The results showed that the number of actinomycetes declined significantly after the treatment of 1,4-DCB at different concentrations, and the amout of bacteria and fungi were significantly decreased in soil samples treated with higher than 200 mg/Kg. 1,4-DCB at over the range of selected concentrations could completely inhibit urease activityin the first 28 days.1,4-DCB at the concentration lower than 100 mg/Kg dried soil stimulated the activity of catalase, while the others showed an inhibition during period of incubation. Results indicated that these two enzymes are sensitive to 1,4-DCB contamination.