The laser-induced breakdown spectroscopy (LIBS) analysis method displays significant matrix effects which greatly hinder the application of this technology. Even if the concentration of a certain element is constant, the physical properties and composition of the sample will affect the element signal. In order to further deepen the understanding of matrix effects, in this paper, the effect of matrix effects (Al matrix and Fe matrix) on the quantitative analysis of Si, Mn, Cr and Cu under different laser defocusing amounts and spectrometer delays is researched. This study found that the matrix effects have different degrees of effect on the analysis line under different experimental parameters. Moreover, the effect of the matrix effects can be reduced by adjusting the laser defocus amount and spectrometer delay. In addition, taking the spectrum generated by the pure sample as the matrix background and subtracting the intensity value of the matrix background at the analysis line can reduce the interference of the matrix effects. After deducting the matrix background, the determination coefficient of mixed quantitative analysis of the three elements Si, Cu, and Cr in Al and Fe matrixes can reach more than 0.99. Besides, for the Mn 257.6 nm, which is severely interfered by the spectrum of the Al matrix and Fe matrix, respectively, the determination coefficient of the mixed quantitative analysis can reach 0.9855.