Abstract: Under the experimental concentration of metsulfuron-methyl bound residues, the change of microbial community structure could be caused in soil. The number of soil bacteria and fungi were increased, while soil actinomyces were inhibited by metsulfuron-methyl bound residues. The maximum inhibitory ratio of soil actinomyces reached 100 percent, and the growth of soil actinomyces did not recovery after incubatior was finished (84 d). The influence of metsulfuron-methyl bound residues on soil microorganisms was differently depended on soil types and incubation time. Soil microbial population, especially soil actinomyces, may be taken as the sensitive indicators for assessing the ecological effect of metsulfuron-methyl bound residues in soils. After nitrogen (urea) was added, the number of soil microorganisms increased, and the toxicity of metsulfuron-methyl bound residues to soil actinomyces decreased.