Abstract:the results from this study show that the contents of Mieyouniaosanhao insecticide (l-"4-chlorophenyl"-3-"2-chlorobenzoyl"urea) in soil under poplar and pine woods dicreased continually, with time and its half life was 12 days. Bacteria and fungi were isolated from forest soil. Bacteria identified to be Pseudomonas testoeteroni, Acinetobacter calcoacticus from poplar forest soil, P. alcaligenes and Acinetobacter calcoaceticus from pine woods soil, as well as fungi were all able to degrade Mieyounaosanhao so that soil microorganism played an important role in degradation of Mieyouniaosanhao. The two metabolites of 4-chlorophenyurea and 4-chloroaniline can be produced from the degradation of this insecticide, and can be also further degraded by soil microorganisms. Therefore, it was concluded that the Mieyouniaosanhao insecticide was easily degraded by soil microorganisms, and it can be used safely without pollution in soil enviroment.