Half-smooth tongue sole(Cynoglossus semilaevis)is a commercially important cultured marine flatfish,in which females grow faster than males.However,under culture conditions,male ratio is higher than female ratio in the half-smooth tongue sole.To find out the reason,one half-smooth tongue sole family is reared for 65 days,from 64 to 129 days postfertilization(dpf)at 17.5,19.5,21.5,23.5,25.5 and 27.5 ℃,respectively.The body size(body length and weight)of the fish was measured on 64,80,103,118,129 and 198 dpf,respectively,and then the relationships between temperature and body size were analyzed by ANOVA and Student-Newman-Keuls.The result showed that the growth rate of tongue sole increased with the increase of temperature from 17.5-25.5 ℃(P<0.05)and then decreased at 25.5-27.5 ℃(P<0.05)on 198 dpf.The Pearson correlation coefficient of temperature and the body lengths and weights of tongue sole were 0.553 and 0.809(P<0.01),respectively.Moreover,the relationship between temperature and the body lengths and weights of tongue sole were described as equations L=2.460 7t^{0.997 9}(R²=0.362 8)and W=9.0×10^-5t^{2.97 6} (R²=0.789 5),respectively.In addition,the gonads of half-smooth tongue sole were analyzed by morphological examination and histological sectioning on 198 dpf.The sex proportions and correlations between temperature and sex determination were analyzed by the method of ANOVA.The result showed that,low temperature(17.5-25.5 ℃) produced a higher proportion of males(27.04%-35.60% females,P>0.05;60.19%-71.53% males,P<0.05).When reared at 27.5 ℃,the proportion of female was up to 53.42%(P<0.05),but 43.49%(P<0.05)of males.At 17.5-27.5 ℃,the temperature was positively correlated with the female(0.349),and the male was negatively correlated(-0.234).The study suggests that temperature plays an important role in the process of sex differentiation and growth of the halfsmooth tongue sole.