Abstract: In order to select a suitable thawing method for frozen Thunnus obesus chunk by studying external and internal heating thawing methods on the quality changes of Thunnus obesus during thawing, including air thawing at normal temperature, vacuum thawing, microwave thawing and ultrasonic thawing. Thawing time, the total viable count, water holding capacity, pH value, salt soluble protein content and SH content were measured during thawing. Among 6 indices, vacuum thawing provided the best tuna quality. After vacuum thawing, water holding capacity, pH value, salt soluble protein content and SH content of the tuna were 63.33% , 6.11, 37.49mg/g and 5.69 ×10 -4 mol·g -1 , respectively. The total viable count was 2.97lg CFU/g, below the industrial standard threshold. Therefore, vacuum thawing was proved to be the most suitable thawing method for frozen Thunnus obesus chunk.