Abstract: To examine the capability of laser-induced breakdown spectroscopy on detection, soil plasma was deduced using Nd: YAG laser under optimal conditions, and then the content of element Cr and Pb in the national standard soil samples was analyzed by the method of plasma atomic emission spectrometry. The calibration curves were respectively drawn with Fe atomic spectral line, spectral lines background and nothing as internal standard. The precision and detection limit of the method were established. The results demonstrate that the values of relative standard deviation of element Cr are 5.85%, 26.48% and 33.10%, and the corresponding values of Pb are 5.42%, 22.78% and 38.66% respectively under these three conditions, which indicates that the internal standard method can improve the precision of the measurement. The detection limits by Fe atomic line as internal standard are 3.5010-3% for Cr and 57.9010-3% for Pb, which meets the requirements of trace element analysis.