The injection water was rich in SO₄^2- in Jiyuan oilfield，which was easy to form insoluble BaSO₄ or SrSO₄ with Ba²⁺ andSr²⁺ in high salinity formation water during injection process. So the nanofiltration membrane was used to remove SO₄^2- and prevent scale formation. The compatibility of source water and formation water as well as the damage to the core were analyzed before and after nanofiltration treatment，and the application effect of this technology was examined in Jiyuan oilfield. The results showed that nanofiltration membrane treatment technology could effectively reduce the content of SO₄^2- in injection water and prevent the formation damage caused by scale. After nanofiltration process，the content of SO₄^2- decreased from 2499.88 mg/L to 428.03 mg /L in source water，and the removal rate of SO₄^2- reached 82.9%. Scaling quantity of nanofiltration water and formation water with different mixing ratio was less than that of source water and formation water mixed，and the inhibition rate of nanofiltration water was 70.4% —74.2% . The core damage rate of source water before and after nanofiltration treatment was 46.13% and 1.47% respectively. Nanofiltration water could effectively suppress the damage to the core. Field test results showed that after nanofiltration treatment，the content of SO₄^2- in injection water at Ji W station reduced more than 80%，the average injection pressure of 36 wells in test area reduced 1.41 MPa，the profile thickness of 11 injection profile test wells increased by an average of 1.35 m，showing good effect.