The invention relates to an element spectral line reverse-extracting method of a laser induced breakdown spectrum, which aims at the bottleneck problem of the laser induced breakdown spectrum as a highest potential element analysis technology so as to improve the track detection limit of a tested element. In the method, background information that changes slowly is extracted, the simultaneous lossless extraction of a plurality of element spectral lines can be effectively achieved, the integrity of information characteristics of all element spectral lines is ensured, the signal noise ratio of a measured spectral signal and the trace detection limit of the tested element are greatly improved, and the improved multiplying ratio of the signal noise ratio of the element spectral line is directly proportional to the removal amount of the background information. The method does not need standard emission spectral lines and linear structures of various extracted elements and the standard background reference spectrums of different measured substrates, achieves the simultaneous extraction of a plurality of element spectral lines within the broad spectrum range and is suitable for the separation and the extraction of element spectral lines of various analyzed matters of various states including gas state, solid state and liquid state that take the laser induced breakdown spectrum technology as a means.