Abstract: Introduces modifying functions of macromolecule polymer to paraffin and asphaltene and studies comprehensively the mechanism of crude oil modifying, colloid rheologics, colloid chemistry and theory of non-electrolyte, and puts forward a new thinking that changes crude oil's homogeneous distribution and make it a non-monophasic colloid, thus forms a light fraction paraffin crystalin-oil, and colloid aggregate. On the basis of maintaining chemicals to do physical action with paraffin, introducing chemical action and coordination chemistry into crude oil modification can not only changes the shape of the colloid and make it into a colloid aggregate but also changes the effect of colloid on paraffin crystal modifier.