Abstract: The effective separation of Sr from Ca is one of the key problem in analysis of ⁹⁰Sr in environment samples. The recovery rate of Sr is more than 80% and the purity is about 99% after the separating condition of Sr from Ca is optimized. ⁹⁰Sr in high salinity ground water was separated and measured by concentrated HNO₃ precipitation method and fuming HNO₃ precipitation method and the result was accordant. The recovery rate and the purity of Sr by concentrated HNO₃ precipitation method is better than by fuming HNO₃ precipitation method. The radioactivity concentration of ⁹⁰Sr in four high salinity groundwater samples is found in the range 1.21-6.24mBq/L by the present method.