The mechanism about separation, purification and dehydration for column chromatography silica gel: there is no much difference between the microcosmic structure of column chromatography silica gel and the general silica gel.SiO2 forming colloidal skeleton is combined in silica tetrahedron and the force field between atoms is in equilibrium. As stated above, silica gel has very high specific surface area，the surface structure of the interspace inside silica gel particle is different from the inner structure of the formed skeleton, the surface silicon atom and the constitutional water contained inside the colloidal gel form silanophilic (Si—OH), i.e. the unbalancedness of this structure causes the surface of silica gel to create free force field, which has adsorption capacity to water molecule or other polar molecule, the surface of colloidal particle has different adsorption capacity on the adsorbed substance due to different strength of polar molecule the adsorbed substance. Because of this regard, silica gel has the selective adsorption on different compound substance. When the component with stronger polar passes through the surface of silica gel, the adsorption strength created with silica gel is also stronger and this component retains on the surface of silica gel for longer time；The other way round, for the component with weaker polar, it retains for shorter time. Therefore, the compound with different substances can be separated due to the different retaining time in process of passing through silica gel. For the strong polar substance, silica gel has strong adsorption capacity on it, such as water molecule. In this case, the molecule of the adsorbed substance can break away from the surface of silica gel by overcoming the potential barrier of gravitational field created on the surface of silica gel only when obtaining enough energy ( for example, heat energy). Thus, at normal conditions, strong polar component is kept inside the interspace of silica gel when compound with strong polar components passes through silica gel column chromatography, which reflects silica gel’s capacity for dehydration & refining or purification of substance.