Abstract: Taking lethal time of high ammonia nitrogen and freshwater tolerance as indices, we estimated the heritability of ammonia nitrogen tolerance and freshwater tolerance of Penaeus monodon. We established 27 full-sib families including five half-sib families of P. monodon based on two breeding populations of P. monodon from Nanhai No.1 and African strain. Besides, we estimated the variance components and genetic parameters for ammonia nitrogen tolerance and freshwater tolerance by using one trait animal model and ASReml software. Then we calculated the estimated breeding values of all animals and families with best linear unbiased prediction. The heritability for ammonia nitrogen tolerance and freshwater tolerance were 0.11±0.04 and 0.29±0.08, respectively (P<0.05). The family phenotypic value correlation coefficients between ammonia nitrogen tolerance and freshwater tolerance was 0.15, showing low linear positive correlation and statistically insignificant difference. The family breeding value correlation coefficients between ammonia nitrogen tolerance and freshwater tolerance was 0.57, showing moderate linear positive correlation and statistically significant difference (P<0.01). Thus, the resistance to freshwater stress can also be improved to some extent with selection of characteristics of ammonia tolerance of P. monodon.