In order to further study salt tolerance performance of a hybrid by Oreochromis niloticus(♀)×Sarotherodon melanotheron(♂)which had been examined and approved by China National Aquaculture Variety Approval Committee as a new variety for aquaculture and named “GILI tilapia”in 2009,researches have been carried out to study the salt tolerance in the chronic salinity stress experiment to GILI tilapia and its two parents,the differences of salt tolerance performance of three kinds of tilapia are analysed,and the regression model between mortality of salt tolerance in the chronic salinity stress and death of time,death of salinity are established.The results of the study show that:(1)There are significant differences in capacity of salt tolerance among three kinds of tilapia,the performance of salt tolerance of GILI tilapia is close to S.melanotheron,it is much higher than O.niloticus,the average death salinity of three kinds of tilapia when they are domesticated in salt are 57.9,66.7 and 18.5 respectively.(2)There are the greatest differences of death time domesticated among individuals in O.niloticus,it is the least in S.melanotheron,it is medium in GILI tilapia.There are the most significant normal negative deviation in GILI tilapia and S.melanotheron,there are the more values of outlier and extremum,O.niloticus has a significant normal positive deviation,it has outlier values,no extremum values.(3)The regression relationships between the mortality of chronic salinity stress to salt and the death time,death salinity of three kinds of tilapia are fit for single-element regression model,the single element regression model between the salt tolerance mortality(Y)and the domestication time of death(t)and salinity of death(s)of GILI tilapia are growth model Y=e^{(-7.694+0.031t)}(R²=0.979)and quadratic model Y=0.542－0.037s+0.001s²(R^2=0.950)respectively.