In order to reduce some of the influence of the matrix effect in the soil on the quantitative analysis of laser-induced breakdown spectroscopy (LIBS ) .Three metals with high purity,Cu,Al and Zn are used as the matrix to assist t he detection of heavy metal elements in the soil by laser-induced breakdown spe c troscopy.First of all,Taking Cd I 288.08nm as the characteristic spectral line for quantitative analysis,after data fitting,the atomic spectral diagrams of t he three metal substrates are obtained,and the plasma characteristic parameters are calculated by the spectral diagrams and related parameters.It can be obtain ed from the data that compared with the tableting conditions,the spectral line intensity under the auxiliary conditions of the three metal substrates is signif icantly enhanced,the calibration curve fitting coefficient R^2is all above 0.97,And the relative standard deviation (RSD) is all below 7%,the element detect ion limit has also been reduced.Finally,the experimental results show that the u se of metal matrix-assisted LIBS detection method will increase the sensitivity of LIBS in the detection of heavy metals in the soil and reduce the detection li mit,which is of great significance for the detection of heavy metals in the soi l.