With the development of Laser Induced Breakdown Spectroscopy(LIBS), increasing numbers of researchers have begun to focus on problems of the application. We are not just satisfied with analyzing what kinds of elements are in the samples but are also eager to accomplish quantitative detection with LIBS. There are several means to improve the limit of detection and stability, which are important to quantitative detection, especially of trace elements, increasing the laser energy and the resolution of spectrometer, using dual pulse setup, vacuuming the ablation environment etc. All of these methods are about to update the hardware system, which is effective but expensive. So we establish the following spectrum data processing methods to improve the trace elements analysis in this paper: spectrum sifting, noise filtering, and peak fitting. There are small algorithms in these three method groups, which we will introduce in detail. Finally,we discuss how these methods affect the results of trace elements detection in an experiment to analyze the lead content in Chinese cabbage. With the development of Laser Induced Breakdown Spectroscopy (LIBS), increasing numbers of researchers have begun focus on problems of the application. We are not just satisfied with something what kinds of elements are in the samples but are also eager to accomplish quantitative detection with LIBS. There are several means to improve the limit of detection and stability, which are important to quantitative detection, especially of trace elements, increasing the laser energy and the resolution of spectrometer, using dual pulse setup, vacuuming the ablation environment etc. All of these methods are about to update the hardware system, which is effective but expensive. So we establish the following spectrum data processing methods to improve the trace elements analysis in this paper: spectrum sifting, noise filtering, and peak fitting. these three method groups, which we will introduce in detail. Finally, we discuss how these these affect affect the results of t race elements detection in an experiment to analyze the lead content in Chinese cabbage.