Objective: Our survey studied about the changes of the limb alignment of patients who suffering from knee osteoarthritis (knee OA) patients with total hip arthroplasty .Methods: A total of 24 patients are in line with the diagnosis of osteoarthritis of the knee, while they have Surgical treatment of hip replacement surgery.were measured before and after surgery in patients with lower limb alignment. Results: 1 .Before and after surgery bilateral hip eccentricity difference, there is a statistically significant difference (P <0.05) difference in length between bilateral and AR values. 2 Before and after surgery, the affected physiological valgus angle I and II and coronal tibiofemoral angle, hip - The knee - ankle angle statistically significant (P <0.05), ankle angle, tibial plateau - backbone angle was no significant difference (P > 0.05). 3 Patients before and after surgery, the knee activity no statistically significant difference (P> 0.05). Conclusion: Total hip arthroplasty patients rebuilt femoral offset, to some extent improved the leg length, change the load center of gravity of the knee. 2 Total hip arthroplasty early changes in the lower limb lines of force, thus affecting the knee load distribution.