Reciprocal hybrids of Platichthys stellatus and Kareius bicoloratus have been reported, however, little is known about the nutritional facts of their muscles. In this study we analyzed the nutritional components in muscles of P. stellatus, K. bicoloratus and the reciprocal hybrids (initial body weight 338.32–445.98 g) using the current national standard methods. We found that the obverse hybrid (P. stellatus♀×K. bicoloratus♂) had significantly higher crude protein content than the inverse (K. bicoloratus♀×P. stellatus♂, P<0.05), but not significantly different from that of P. stellatus and K. bicoloratus (P>0.05). The crude lipid content of the obverse hybrid (1.44%) was significantly higher than that of the other three species (P<0.05). The inverse hybrid had the lowest level of crude lipid (0.43%) and significantly higher moisture level than the other three species. There was no significant difference in the muscle ash content among the four species (P>0.05). The obverse hybrid had significantly lower juice loss yield, water loss yield and fat loss yield than P. stellatus and K. bicoloratus (P<0.05), and its cooked meat yield was obviously higher than that of the inverse hybrid (P<0.05). The obverse hybrid possessed the highest contents of essential amino acid, delicious amino acid and total amino acid, and its ratio of branched-chain amino acid amount to aromatic amino acid amount was close to the normal value in humans. The contents of essential amino acids in the four species were higher than the Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO) standard, moreover, it was the highest in the obverse hybrid of which the level was even higher than egg protein standard. The obverse hybrid had remarkably higher amino acids score (AAS), chemical score (CS) and essential amino acid index (EAAI) than the other three species, whereas the inverse hybrid had the lowest scores. These findings indicated that the obverse hybrid showed apparent hybrid advantages and exhibited higher nutritional values and muscle qualities than P. stellatus and K. bicoloratus. However these advantages were not present in the inverse hybrid. Our study provided valuable information for the selection of traits in the breeding between P. stellatus and K. bicoloratus.