In this paper, optical spectroscopy could uses for medical devices, UV-Vis, photoluminescence(PL) and laser induced fluorescence spectroscopy(LIF) are employed to investigate different concentration of urea. The effect of urea concentration on the emission wavelength of dyes(RdB,Rd6G, Methylene Blue) was investigated by using LIF. It is shown that increasing in urea concentration leads to decrease in the photoluminescence spectrum and increase in absorbance spectrum. In the study of the effect of urea concentration on the emission wavelength of methylene blue, increasing in urea concentration in this dye caused blue spectral shift and in the two other dyes the spectral shift have not been observed, it could find urea has no direct reaction with these dyes.