This treatise introduces the results of the auther's research in using the method of SAXS (the small angle X-ray scattering) on the structure of the liquid-crystal system made from micro-hydro cephalin with water, methanol and ethanol respectively. Experiments reveal to us the following phenomena: in the cephalin-water system when the content of water increases, the repeat distance of bilayers in the liquid-crystal system of cephalin and water widens and in the cephalin-methanol and cephalin-ethanol system, when the content of alcohol increases the repeat distance narrows; according to the multiplies of hydro-carbon chain in alcohol, the repeat distance varies from wider to narrower, then vanishes gradually and at last the liquid-crystal phase changes into liquid phase. Therefore it is quite clear that water and alcohol exert different influence on the repeat distance of liquid-crystal phase of cephalin.