AIM:To study the optical properties of human normal smallintestine tissue at 476.5 nm,488 nm,496.5 nm,514.5 nm,532 nm,808 nm wavelengths of laser irradiation.METHODS:A double-integrating-sphere system,the basicprinciple of measuring technology of light radiation,and anoptical model of biological tissues were used in the study.RESULTS:The results of measurement showed that therewere no significant differences in the absorption coefficientsof human normal small intestine tissue at 476.5 nm,488 nm,496.5 nm laser in the Kubelka-Munk two-flux model (P>0.05).The absorption coefficients of the tissue at 514.5 nm,532 nm,808 nm laser irradiation were obviously increased with thedecrease of these wavelengths.The scattering coefficientsof the tissue at 476.5 nm,488 nm,496.5 nm laser irradiationwere increased with the decrease of these wavelengths.The scattering coefficients at 496.5 nm,514.5 nm,532 nmlaser irradiation were obviously increased with the increaseof these wavelengths.The scattering coefficient of the tissueat 532 nm laser irradiation was bigger than that at 808 nm.There were no significant differences in the total attenuationcoefficient of the tissue at 476.5 nm and 488 nm laserirradiation (P>0.05).The total attenuation coefficient of thetissue at 488 nm,496.5 nm,514.5 nm,532 nm,808 nmlaser irradiation was obviously increased with the decreaseof these wavelengths,and their effective attenuationcoefficient revealed the same trend.There were no significantdifferences among the forward scattered photon fluxe,backward scattered photon fluxe,and total scattered photonfluxe of the tissue at 476.5 nm,488 nm,496.5 nm laserirradiation.They were all obviously increased with attenuationof tissue thickness.The attenuations of forward andbackward scattered photon fluxes,and the total scatteredphoton fluxe of the tissue at 514.5 nm laser irradiation wereslower than those at 476.5 nm,488 nm,496.5 nm laserirradiation respectively.The attenuations of forward andbackward scattered photon fluxes,and total scattered photonfluxes at 532 nm laser irradiation were obviously slower than those at 476.5 nm,488 nm,496.5 nm,514.5 nm laserirradiation.The attenuations of forward and backwardscattered photon fluxes,and total scattered photon fluxe at808 nm laser irradiation were all obviously slower than thoseat 476.5 nm,488 nm,496.5 nm,514.5 nm,532 nm laserirradiation respectively.CONCLUSION:There are significant differences in opticalparameters of human normal small intestine tissue in theKubelka-Munk two-flux model at six different wavelengthsof laser radiation.The results would provide a new methodof information analysis for clinical diagnosis. AIM: To study the optical properties of human normal smallintestine tissue at 476.5 nm, 488 nm, 496.5 nm, 514.5 nm, 532 nm, 808 nm wavelengths of laser irradiation. METHODS: A double-integrating-sphere system, the basic principle of measuring technology of light radiation, and an optical model of biological tissues were used in the study .RESULTS: The results of measurement showed that therewe no significant differences in the absorption coefficients of human normal small intestine tissue at 476.5 nm, 488 nm, 496.5 nm laser in the Kubelka -Munk two-flux model (P> 0.05). The absorption coefficients of the tissue at 514.5 nm, 532 nm, 808 nm laser irradiation were were increased with the displacement of these wavelengths. The scattering coefficients of the tissue at 476.5 nm, 488 nm, 496.5 nm laser irradiationwere increased with the decrease of these wavelengths. The scattering coefficients at 496.5 nm, 514.5 nm, 532 nmlaser irradiation were obviously increased with the increase of these wavelengths. oefficient of the tissueat 532 nm laser irradiation was bigger than that at 808 nm. There was no significant differences in the total attenuation coefficient of the tissue at 476.5 nm and 488 nm laserirradiation (P> 0.05). The total attenuation coefficient of the tissue at 488 nm , 496.5 nm, 514.5 nm, 532 nm, 808 nm laser irradiation was significantly increased with the decrease of these wavelengths, and their effective attenuation efficiency showed the same trend. There were no significant differences among the forward scattered photon fluxe, backward scattered photon fluxe, and total scattered photonfluxe of the tissue at 476.5 nm, 488 nm, 496.5 nm laserirradiation. They were all increased increased with attenuation of tissue thickness. The attenuations of forward and backward scattered photon fluxes, and the total scattered photon flux of the tissue at 514.5 nm laser irradiation wereslower than those at 476.5 nm, 488 nm, 496.5 nm laserirradiation respectively. The attenuations of forward and backward scatteredphoton fluxes, and total scattered photon flux at 532 nm laser irradiation were obviously slower than those at 476.5 nm, 488 nm, 496.5 nm, 514.5 nm laserirradiation. The attenuations of forward and backwardscattered photon fluxes, and total scattered photon fluxe at808 nm laser irradiation were all obviously slower than thoseat 476.5 nm, 488 nm, 496.5 nm, 514.5 nm, 532 nm laserirradiation respectively. CONCLUSION: There are significant differences in opticalparameters of human normal small intestine tissue in the Kubelka-Munk two-flux model at six different wavelengths of laser radiation The results will provide a new method of information analysis for clinical diagnosis.