Abstract: To scientifically evaluate the nutritional components and flavor substances of different muscle parts of bigeye tuna, yellowfin tuna and bluefin tuna, the differences among different species and parts of three tuna species were compared through basic nutrients, amino acid composition, fatty acid composition and volatile flavor substances, which detected using national standard method and gas chromatography-ion migration spectrometer. The results showed that moisture content of three tuna species was quite different. The moisture content of different muscle parts was varied from 50.16 to 79.37 g/100 g, while the moisture content of bluefin tuna was significantly lower than the other two tuna species (P<0.05). The dorsal muscle of bluefin tuna had the highest protein content (24.70 g/100 g), while the abdominal muscle of bluefin tuna had the highest fat content (30.29 g/100 g). The dorsal muscle of bigeye tuna met the FAO/WHO standard, so it was regarded as the high-quality protein. While the abdominal muscle of bigeye tuna, the dorsal and abdominal muscles of bluefin tuna were close to the FAO/WHO standard, they were regarded as good protein sources. The content of glutamic acid was the highest in the three tuna species, while tryptophan was the lowest. A total of 31 kinds of fatty acids were detected in the three tuna species, including 13 saturated fatty acids, 8 monounsaturated fatty acids and 10 polyunsaturated fatty acids, while the total proportion of DHA and EPA in total fatty acid was 27.61%~41.73%. There were 40 kinds of volatile flavor compounds were detected, including aldehydes, ketones, alcohols, esters, acids, alkanes and nitrogen compounds. Bluefin tuna had the most kinds of volatile compounds, while bigeye tuna had the fewest. The relative contents of volatile compounds in different muscle parts of the same species were also significantly different. The muscles of three tuna species had high nutritional value and different aroma profile. The dorsal muscle of bluefin tuna had high essential amino acid content, while the abdominal muscle had rich unsaturated fatty acid, and better aroma profile. The results provided a reference for the precision processing and utilization of different muscle parts of three tuna species.