Abstract: To investigate the effect of root exudates of Sudan grass (Sorghum sudanense) on OCPs dissipation,pot experiments were carried out by simulating a gradually decreasing concentration of root exudates with the distance away from root surface in rhizosphere. The influence of root exudates on the degradation of organochlorine pesticides (OCPs) in soils was determined,microbial ecological characteristics in OCPs-contaminated soils were evaluated.The results showed that Sudan grass root exudates stimulated OCPs degradation significantly at their initial concentrations ranging from 0 to 336.48 mg·kg-1 after 20 days of simulating phytoremediation.Among all treatments,the degradation rate in the root exudates-soil system (TR2) was of the highest,79.21% of OCPs were removed from the soils averagely and was 36.43% higher than that of CK (e.g.,spiked soil),and 52.28% higher than that of TR1 (e.g.,spiked soil with addition of 0.05% NaN3) while 30 mL exudates with 246 mgTOC·L-1 was added.Soil microbial biomass carbon in the root exudates-soil system was also of the highest and there was close relation between OCPs degradation and soil microbes during the whole experiments.In the test soils which phospholipid fatty acids were probed and analyzed by the means of GC-MS,the microbial community was dominated by bacteria,and followed by fungi,and the variation trend was consistent with different OCPs degradation levels,which indicated that the OCPs was degraded mainly by bacteria,and the effect of root exudates on OCPs degradation was mainly carried out through the effects on bacteria and fungi population.Thus,the root exudates of Sudan grass might change microbial ecological characteristics in the process of phytoremediation by promoting the rhizosphere microbial growth and modifying the community structure,and are the key regulators in rhizosphere communication which can modify the biological and physical interactions between roots and soil organisms,and then enhance the degradation of OCPs in soils.