Abstract: We conducted two gillnet fishery surveys in northern South China Sea in 2012 to investigate the relationship between the body characteristics of Scomberomorus commersoni and the mesh size. The captured species and the body characteristic of S.commersoni are analyzed, and the relationship between the body characteristic of S.commersoni and the mesh size is investigated by the relative body girth, according to the captured way. The results indicate there are 22 catch species; S.commersoni accounts for 57.33% to the total landing; the captured position in body of S.commersoni is between opercula and the beginning of the second dorsal fin. The relative body girth ratio of S.commersoni lies in the range of 0.96~1.77, while the relative body girth ratio 1.09 is optimum for S.commersoni catch.