This study assessed the thermal tolerance of 40 turbot families. Growth and upper thermal tolerance traits were recorded. The upper thermal tolerance trait was analyzed using variance analysis, correlation analysis and variance component analysis. Analysis of the two growth stages showed that among the 40 families studied, within the first growth stage, six families showed rapid growth, 26 families showed secondarily rapid growth, and eight families showed common growth. Within the second stage, nine families showed fast growth, 28 families showed secondarily rapid growth, and three families showed common growth. Only one family showed rapid growth over both stages. Analysis of the upper thermal tolerance trait showed that upper thermal tolerance ranged from 836.30–1 367.30℃·h with a total mean of 1 113.00℃·h. Three high heat resistance families were identified. The family with the highest heat resistance was shown to have a mean upper thermal tolerance of 1 367.30℃·h. Five non heat resistance families were identified, with a thermal tolerance of 836.30℃·h identified for the family displaying the lowest mean of upper thermal tolerance. The results of ANOVA showed that there was a significant difference in upper thermal tolerance among the different families studied (P<0.01). The correlation analysis showed a different phenotypic correlation between growth rate at different growth period compared to growth rate and upper thermal tolerance.