The invention relates to the field of laser-induced breakdown spectroscopy data pretreatment analysis. Specifically, with the method, based on a reasonable spectral peak mathematical model, with an unconstrained optimization algorithm, spectral peak related information after overlapped peak resolution is obtained by calculation. According to the method, based on a spectral peak mathematical model, and with an unconstrained optimization algorithm, spectral line related information after overlapped peak resolution is obtained by calculation, and overlapped spectral lines are separated. According to the invention, selective calculation can be carried out according to actual spectral line situations, and spectral line information can be determined with a small amount of parameters. Therefore, sample component analysis performance and accuracy are improved. Spectral peak position is visually selected, and initialization parameters needed by all optimization algorithms can be determined. The method also has the advantages of high calculation speed and easy implementation. With the method, a final processing result is selected by visual comparison, such that substance component quantitative analysis accuracy is improved.