Abstract: To research the relation of oil's laser induced fluorescence(LIF) intensity and oil temperature, the third(355 nm) harmonics pulsed Nd: YAG laser was used as the exciting source, and a multi track spectrology as the detector, and the intensities of laser induced fluorescence(LIF) of oil under different temperatures were measured. The oil temperature was controlled by water bath. The results of the experiment were analysed with quantum physics and the theory of fluorescence bringing. It was shown that for an invariant exciting spectra, the intensity of laser induced fluorescence drops with the increasing of temperature.