Abstract: Anise oil is a natural spice in Guangxi. Isolation of trans-anethole degrading bacterial strains and trans-anethole biotransformation process were performed using anise oil as the only carbon source. The target strains were expected to produce high value-added nature spice and medicine intermediate by biotransformation of trans-anethole—the main constituent of anise oil. Bacteria were isolated from soil under aniseed trees by enrichment culture. Then biotransformation of trans-anethole to anisaldehyde or anisic acid with these strains were carried out by fermentation. The contents of trans-anethole，anisaldehyde and anisic acid in the culture broth were analyzed by the methods of TLC，photometry and HPLC determined. The isolated bacterial strain BT-13 had good capability to biotransform trans-anethole to anisic acid. This strain was identified as Pseudomonas sp. according to visual observation，physiological and biochemical experiments and 16S rDNA sequence analysis.