According to the spectral line broadening mechanism of laser induced breakdown spectroscopy, the emission lines from the standard spectral database of NIST were simulated, and they were compared with the spectral data of experiment. In the process of comparison similarity measure was used to measure the similarity between the simulative spectra and the experimental spectra. The automatic recognition method of elemental spectra was studied, and the spectral data of soil between 340 and 345 nm was recognized by computing the proportional coefficients of the spectral lines Using principle of nonlinear least squares, the recognition process was completed. The feasibility and the advantage of the method were proved by the results of experiment.