Abstract: Planar laser induced fluorescence (PLIF) is the most intuitive and effective measurement technology, which shows a broad application prospects in the complex combustion flow field diagnostics because of its abundant information, non-contact, high spatial and temporal resolutions, visualization and other advantages. PLIF technology can provide a two-dimensional imaging and many parameters such as temperature, velocity, component concentration and pressure of some special cross-section in the flame and other flows. A two-excitation planar laser-induced fluorescence (PLIF) system was set up based on the two line PLIF technology. Two dimensional instantaneous temperature distribution of premixed CH4/air flame was measured quantitative by picking two proper spectrum lines. In experiments, by acquiring the power of laser pulses and the profile distribution and revising the spatial positions of the ICCD imaging, the precision was elevated. The measurement results are more precise compared with the results of thermoelectric couple and the uncertainty is less than 5%, which can suffice with the applications in supersonic combustion diagnostics.