The basic idea of LIF is simple. Light from a tunable laser impinged on the sample is to be investigated. As the frequency of the laser is changed, molecules within the irradiated portion of the sample will be excited to fluorescence whenever the spectral envelope of the laser overlaps an absorption line of the molecule [5]. Since the only excited molecules are those in the specific lower level(s) of the corresponding transition, the excitation is selective for this state or group of states. Hence, the "excitation spectrum" obtained by recording the fluorescent intensity as a function of wavelength reflects the relative populations of these different states. The excitation spectrum depends on the factors of environmental conditions such as concentration, temperature, pH value, molecular structure and solvent effect [6-8]. This experiment aims to study the effect of concentrations, temperature and solvent on the luminescence decays of fluorescence orange dye at different concentrations and temperatures by comparing the fluorescence properties of dye to the level of concentration and temperature in