Laser induced breakdown spectroscopy(LIBS) was applied to measure barium and strontium elements in soil. The emission spectrum was emitted as the plasma was cooling off, which was collected and analyzed by fiber spectrometer. Spectral lines of barium(BaII line at 455.41 nm) and strontium(SrI line at 460.73 nm) were separately used for the determining. In order to reduce the error, fitting of the spectra by using Lorenizian function was used, the datum was preprocessed and the net intensity value of the spectra was collected. A signal intensity in the proper range of the characteristic spectrum was chosen as the interior label. A calibration curve was drawn according to the ratio between the value of the analytical line and the interior scaling line . The correlation coefficient between the content and the intensity ratio of Ba and Sr were up to 0.990 0 and 0.990 6. The content of Ba and Sr was inversed by means of the intensity scaling method .As a result , the relative deviations between the content values and the standard values of Ba and Sr were 5.7% and 5.1% respectively.