Abstract: In view of the current shortages of chemical cross-linking gel and bulk particle plugging agent, which are difficult to control gelling and match the formation pore size. By introducing quaternary ammonium salt hydrophobic functional group it has eighteen atoms of carbon to polyacrylamide side chain, a new type of profile modification gel system basing on inter molecular physical cross-link is designed. The characteristic of molecular structure, the micro-aggregation morphology and property in aqueous solution are characterized and evaluated. The results show that the hydrophobic functional group of physical cross-linking gel system aggregated spontaneously in aqueous solution, produced physical crosslinking, formed dense network aggregate, and the aggregate network size is between 200-400 nm. It is qualified with better viscidity, viscoelasticity and shear resistance compared with chemical cross-linking gel, at the same time by adjusting the content of hydrophobic functional group, formation colloid time can be adjusted. The non cross-linked particle is injected into strata where there is big pore, the particle can produce physical crosslinking in the core, which can plug the high permeability zone effectively. The intermolecular force of physical crosslink is weaker than covalent bond of chemical crosslink, so the system is qualified with certain ability of migration in the formation. The physical crosslink system has the properties of profile control and flooding. It is a new type of promising efficient plugging and profile control system.