Abstract: Effect of vacuum-steam thawing on the quality changes of tuna (Thunnus obesus) were studied in this paper.Tuna was thawed by different vacuum degree of 70, 50, 30, 10kPa, respectively.The general rules of vacuum-steam thawing would be established by measuring physical and chemical indices of tuna in 48h which after thawing.The results suggested that vacuum-steam thawing could accelerate the thawing rate, reduce the thawing time.The central temperature of a tuna block which weight 100g and 5cm in thickness raised from-40℃ to-5℃ cost 1750s under the condition of 10kPa, 20℃, which took half the time of air thawing.Quality of tuna thawed by vacuum-steam was better than which thawed in air due to the good water holding capacity, protein and texture.At the same time, the higher the vacuum degree of thawing was, the better the thawing result would be.During the storage period of 48h, a tuna block vacuum-steam thawed under 10kPa had better quality than other experimental groups:salt- extractable protein content was 26.81mg /g and SH content was 4.52 × 10- 4mol·g- 1, water holding capacity was 60.91%, hardness was 142.83g, springiness was 0.7769 and chewiness was 74.86, respectively.