Objective To study the influence of using high sodium and gradient ultrafiltration in on-line hemodiafiltration on blood pressure. Methods In a cross-section study, about 60 times on-line HDF of 10 ESRD patients were separated into two groups as group A:using high sodium and gradient ultrafiltration in on-line HDF(n=30) and group B:without using high sodium and gradient ultrafiltration in on-line HDF(n=30). Blood pressure of the 1st hour、2nd hour、3rd hour、4th hour and the lowest blood pressare in each group were compared between the two groups. Result There was significant difference of the blood pressure in the 1st hour、2nd hour、3rd hour and the lowest blood pressure between group A and group B (P<0.05). There was no significant difference of the 4th hour's blood pressure between the two groups. (P=0.293). Conclusion Using high sodium and gradient ultrafiltration in on-line HDF could make the blood pressure and hemodynamics more stable than in HDF without using.