Abstract: The cell free preparation, extracted from Alcaligenes sp. YF11 capable of degrading the target pesticides, was immobilized with Ca alginate. Degradative nature of the immobilized enzyme was then determined with fenvalerate as substrate. The optimal occurred at pH8.0 and temperature of 35℃. Km for degradation of fenvalerate was measured to be 55.0nmol/ml. An immobilized enzyme column was examined for its use in detoxification of fenvalerate at flow rate of 4ml/min under temperature of 25℃, 61.3% 90% of fenvalerate were removed at concentrations of 3.1 200mg/ml.