The diffuse reflectance and transmittance of human arteries and veins were studied with 632.8 nm of He-Ne laser. The measurements were performed with two standard integrating sphere systems. The absorption coefficient, scattering coefficient and the changes of total optical intensities I(x), forward scattering flux i(x), backward scattering flux j(x) as a function of thickness of human arteries and veins were evaluated and analyzed from the experimented data by Kubelka-Munk model. The results of measurement showed significant difference of diffuse reflectance and transmittance between arteries and veins at 632.8 nm wavelength of He-Ne laser. Furthermore, the absorption coefficient and the scattering coefficient of arteries were obviously bigger than that of veins at He-Ne laser wavelength. The changes of I(x), i(x) and j(x) as a function of thickness of human arteries and veins were also significant difference.