Abstract:In order to rationally develop and utilize Thunnus obesus，the basic nutrients，amino acid composition，fatty acid composition and mineral composition of Thunnus obesus were analyzed in this study. The results showed that there was no significant difference in water content and crude protein content in the muscles of the four parts of Thunnus obesus. The water content in the head muscle was the lowest （73.22 g/100 g），and the crude fat content （4.56 g/100 g） and ash content （1.73 g/100 g） were the highest. The crude protein content in the back muscle was the highest （22.52 g/100 g），and the water content in the belly muscle was the highest（75.15 g/100 g），and the crude protein content was the lowest （21.63 g/100 g）. The content of essential amino acids （7.17 g/100g and7.34 g/100g） in the head muscle and back muscle was significantly higher than that in the belly muscle and tail muscle. The essential amino acid index （EAAI） was greater than 0.75 in the head muscle and back muscle，which were good protein sources. The content of saturated fatty acids （55.08 g/100g）and monounsaturated fatty acids （23.94 g/100 g） in the tail muscle was significantly higher than that in the other parts. The content of polyunsaturated fatty acids in the head muscle （47.36 g/100 g） was significantly higher than that in other parts，and the polyunsaturated fatty acids were mainly docosahexaenoic acid （DHA）and eicosapentaenoic acid （EPA）. Among the mineral elements，Na and K showed higher content in the muscle from different parts of T. obesus，and the content of Na in the tail muscle was the highest （8 771.57 mg/100 g），which was significantly higher than that in other parts. The K content in the head muscle and belly muscle was 4 963.64 mg/100 g and 5 017.58 mg/100 g，respectively，which was significantly higher than that in the back muscle and tail muscle. The content of Zn in the tail muscle （13.41 mg/100 g） was significantly higher than that in other parts. The Se content in the head muscle （1.40 mg/100 g） was significantly higher than that in the other parts. In conclusion，the muscle from the four parts of T. obesus was rich in nutrients and had high nutritional value. The detection of nutrients was of great significance for the further research and development of T. obesus.