This study investigated the effects of dredging on the water quality, the quantity of plankton and microbe, and the toxicity of sediment. The results were as follows: after dredging, the water quality was improved; the concentration of heavy metal in water held the line; the variety of the microbe quantity was not obvious and might be recovered soon; and the toxicity of sediment was relatively weak, it included that the toxicity of sediment for the luminescent bacteria was depressed; the death rate of animal declined; the rate of liver in avoirdupois declined; and the rate of exceptional mouse sperm declined. It is suggested that dredging in Suzhou creek helped for the recovery of the aquatic ecosystem.