In order to understand the result confidence interval in the flame atomic absorption emission spectrometric determination of Strontium content in mineral water, according to the measurement result uncertainty evaluation principle, the sources of uncertainty were analyzed, the main components of the uncertainty in the determination were reasonably evaluated, and the combined standard uncertainty and expanded uncertainty were evaluated. The results showed that: to the mineral water samples with strontium content of 0.225 ug/ml, the expanded uncertainty is 0.028 ug/ml.