In China, most of undeveloped oil reserves are low and ultra low permeability reservoirs. The total remaining petroleum reserves of CNPC is about 4.07×107m3, and the low and ultra low permeability reserves is 3.16×107m3, So it is important to reasonable develop the oil reserves to keep the petroleum output stable. Under the low permeability layer condition, it is difficult to inject water to the formation, and the output of oil well is very low. The chemical agent can solve the difficulty of injection water and enhance the oil recovery. The relative permeability experiments shows irreducible oil was reduced by the wettability alteration agents, and the mobile oil saturation increased, which enlarging the range of the two phases co-flowing and enhancing oil recovery. As a result with alteration agents, the cross-point relative permeability moves to right, and the core converts to water-wet. In daqing oil field test, the water injection pressure is reduced by 15%, and the term of validity is more than 10 months.