In order to improve the quality of Litopenaeus vannamei seedlings and explore the application of mass selection and crossbreeding methods in large-scale production of artificial breeding,a comparative study on inbred and hybrid offsprings within stock A was carried out.Stock A was introduced from America in 2008 and was then artificially selected for two generations.Stock B was selected from Guangdong cultured population in 2010.The inbred line AA(A♀?A♂)and reciprocal cross lines AB(A♀?B♂)and BA(B♀?A♂)between these two stocks were established.Then a comparative study on growth,low-salinity and low-temperature resistance at larval stages was conducted among these three lines.The results showed that the offsprings for AB showed the best resistance capacity of low-temperature and lowsalinity among three lines.Under the low temperature of(13.0?0.9) ℃ and the low-salinity of 4.7 conditions,the survival rates for AB line was 27.5% and 64.6% higher than that of the inbred line AA,respectively.The growth rate for body weight at the grow-out stage were (253?55) mg/d for AB line,(208?52) mg/d for BA line and (219?36) mg/d for AA line.The growth rate for AB line was 21.6% and 15.5% faster than that of BA and AA lines.The results indicated that heterosis of Litopenaeus vannamei was closely related with mass selection for broodstock.