Abstract: The paper present an investigation on the characteristic of laser light transporting in human artery and vein with the aid of the primary theories of photo-biology,elementary medical science and physics. Diffuse reflectance R and transmittance T of human artery and vein samples is measured by a standard integrating spheres system,using He-Ne laser in 632.8nm wavelength and the absorbance A was deduced. The scattering phase function S(θ) is obtained by the experimental arrangement repacked from a spectroscope at angles from -90°to 90°for human artery and vein samples in 632.8nm wavelength and the mean cosines of scatter μ was calculated. The results show that the attenuation of the transmitted light intensity with sample thickness satisfy exponential attenuation by low power(P<20mW) laser radiation for human artery and vein and scattering of light in human artery and vein is highly converse peaked.