Abstract: In this paper, single-factor test combined with orthogonal test were used to study the optimum condition of ultrasonic extraction and enzymatic hydrolysis on taurine from Crassostrea hongkongensis, and the ultrasonic -assisted enzymatic hydrolysis under the optimal condition was investigated simultaneously, in which the taurine yield was used as the indexes. The optimized conditions for ultrasonic extraction were obtained as extraction time of 40 min, ultrasonic power of 825 W, extraction temperature of 70℃ and the taurine yield was 0.276（±0.013)%. The alkaline protease was selected as the optimum enzyme and the optimum condition was obtained as enzyme amount of 4 000 U/g, ratio of material to solvent of 1:2 (g/mL), hydrolysis time of 6 h and the taurine yield was 0.746 (±0.053)%, which was significantly higher than that of ultrasonic extraction. The taurie yield of ultrasonic-assisted enzymatic hydrolysis (0.782 ±0.023%) was higher than that of alkaline protease hydrolysis, which indicated that ultrasonic -assisted enzymatic hydrolysis could be an effective technique for oyster taurine extraction.