The influence of different chlorsulfuron concentration on the soil microbial community structure was detected with fatty acid methyl ester(FAME) analysis and viable count.The result showed that soil microbial community changed after treatment of chlorsulfuron.Actinomycetes were inhibited firstly when the soil was incubated with chlorsulfuron 1 d,but bacteria and fungi had no significant change.Then both actinomycetes and bacteria were inhibited when the soil was incubated with chlorsulfuron 45 d,fungi had no significant change (P<0.05).The result of chlorsulfuron on microbial community structure detected with FAME analysis was consistent with that of the viable count.The order of microbial sensitivity to chlorsulfuron was actinomycetes>bacteria>fungi,and bacteria had some tolerant capacity toward chlorsulfuron.