In order to evaluate success in selective breeding of Scophthalmus maximus, the nonlinear growth curves of a selected fast-growing strain and the common cultured strain were fitted using Chapman-Richards (C-R) model, and the differences in growth performance of the two strains have been deeply investigated. The results showed that the goodness of fit (R²), time to inflection, weight at inflection and maximum month gain of fast-growing strain and common cultured strain were respectively 0.999 and 0.997, 15.228 and 16.858 months old, 716.712 and 619.862 g, 111.711 and 78.061 g. The instantaneous growth rate, growth acceleration rate and relative growth rate of fast-growing strain were higher than those of common cultured strain during months of 4.5–25, 3–13.8 and 3–15 months old, respectively. However, the instantaneous growth rate and growth acceleration rate of fast-growing strain were lower than those of common cultured strain in other growth stages, and the relative growth rate is almost the same. Furthermore, the fast-growing strain showed earlier starting point (9.05 months old), inflection point (15.23 months old) and ending point (21.40 months old), shorter fast-growing period time interval (12.35 months old) and longer fast-growing body weight intervals (1 187.680 g) than those of common cultured strain. Obviously, the selected fast-growing strain has obtained greater net body weight increment during fast-growing period in a relatively short time.