Abstract: The strain D4 was identified as <em<Enterobacter</em< sp. according to its morphological characteristics and 16S rDNA sequence. Based on the single factor experiments, biodegradation conditions of the strain D4 were modeled and optimized by Plackett-Burman design (PB) and response surface method. The rotation speed, dibenzothiophene (DBT) concentration and reaction temperature were then selected as significant degradation factors. The optimal conditions for degradation were determined as follows:175 r/min of rotation speed, 0.1 mmol/L of dibenzothiophene concentration and 30 ℃ of culture temperature. Under the optimum conditions, the degradation rate was 59.83%, approximately 10% higher than that under original conditions.