By the use of Rheological changes in different pH values, one could efficient oil recovery by using hydrogel solutions sweeping. The hydrogel is sensitive to pH values and the gelation point changed by the pH, results show that in acidic and neutralized pH the swelling ratio of hydrogel same as their mobility increased. According to this results the shape of hydrogel imagined as a 3-d core-shell; which are placed in layers. By swelling the viscosity of system downed, this hydrogel then used as a second fluid for sweeping crude oil in E.O.R (enhancement oil recovery). Viscosity of gel was measured by a Brookfield viscometer and in different shear rate the viscosity changes and shearthining behavior also observed.