Abstract: To explore the effects of quinclorac, a common herbicide in paddy field, on soil enzymes activities and microbial community structure, soil samples from non -flooded paddy soil and flooded paddy soil were supplemented with various concentrations of quinclorac and kept in the dark at 25℃. The results showed that the catalase activity was significantly activated by quinloarc in the flooded soil. The change trend of other three enzymes activities, urease, dehydrogenase and cellulose, were similar to the control, in spite of some change occurred in the three enzymes. PLFA biomass of bacteria was much more than that of fungi. The correlation analysis showed that there was a significantly positive relationship between catalase and 23：0 of soil fatty acid. After the non-flooded soil were treated with quinclorac, analysis of the correlation between enzymes activities and soil PLFAs indicated that, urease, catalase, dehydrogenase and cellulase were regulated mostly by the microorganisms which contained 12：0, 14： 0, 14：1, 15：1, 16：1, 17：1, 22：0, 24：0 and 18：1n9t, and there was a significantly negative relationship between total PLFA biomass in soil and catalase and urease, but a positive relationship between total PLFA biomass and dehydrogenase and cellulose.