A fractional laser-induced plasma (LIBS) spectral detection method for SF6 gas leakage, the system used in the method consists of an embedded system host (18), a high-energy pulse laser (1), a beam expander (3), and a focusing lens Array (5), beam splitter (6), photodetector array (10), drive amplification output circuit (11), acousto-optic tunable filter (12), AOTF drive controller (13), lens (19) composition. The invention adopts lattice LIBS technology to analyze the LIBS signals of sulfur and fluorine elements in real time at multiple points in the monitoring area, and then judge whether there is SF6 gas leakage and the approximate concentration distribution of SF6 gas leakage. The invention adopts lattice LIBS measurement, which is more efficient than single-point measurement; LIBS spectrum analysis adopts AOTF to select two wavelengths, without the need of conventional spectrometer for light separation and spectrum analysis, which saves analysis time and improves real-time performance. In addition to judging whether there is SF6 gas leakage, it can also analyze the approximate concentration distribution of SF6 gas leakage.