This paper focuses on obtaining the intrinsic laser induced autofluorescence (LIAF) spectra by using reflectance spectra to minimize the effect of the absorption and scattering of tissue.The correlation between fluorescence distortion coefficient f and reflectance spectra R has been studied by Monte Carlo(MC) simulation.The results show that R represents a very good approximation of f for tissue fluorescence spectra correction.Corrected fluorescence spectra were calculated by dividing the measured LIAF spectra by the diffuse reflectance R.The corrected fluorscence spectra for normal tissue exhibit two emission peaks at wavelength 420 nm and 475 nm,respectively,while one emission peak at 425 nm was recorded for the corrected spectra of the cancerous tissue.We proposed that the difference between spectra from normal tissue and adenoma was caused by the less NADH concentration in adenoma than that in normal tissue.