Abstract: According to the characteristics of low permeability and fracturing reservoirs in Jilin Oilfield,a compound profile modification agent called HSG was developed in EOR Center of China University of Petroleum.The apparent viscosity of HSG sol rises with increased copolymer,salinity and alkali concentration under the same sheer rate.The HSG sol also had a property of shear thinning.Viscosity vs.temperature test showed its apparent viscosity decreased with increased temperature.The yield stress of HSG gel was 3500 Pa.Linear viscoelasticity area was determined by oscillation shear sweep test and strong gel property of this sol was shown.The injection test of two parallel connection sand-packed pipes showed that the sol had the attribute of preferentially entering high permeability zone.Profiling experiment with 20-meter sand-packed pipe showed the injection pressure gradient of this sol was 0.82 MPa/m,and the gel had a strong shut-off property with a shut-off intension of 17.54 MPa/m.