【Abstract】Objective：The effect of rotation apex distance and neck-shaft angle on limb length and offset during hip arthroplasty were retrospectively analyzed.To provide guidance for the control of limb length and offset in hip arthroplasty. Methods: From June 2019 to December 2020, 117 patients with unilateral hip replacement were collected. The neck-shaft angle of the healthy side and the prosthesis were measured in the standard hip X-ray films. Then take the difference between the angle of the healthy side and the affected side, Patients with ± 5 ° or less were in group 1, patients with less - 5 °were in group 2, and patients with more + 5 °were in group 3. We measured the bilateral offset, large tear distance (the distance between the high point of greater trochanter and the tear drop line), small tear distance (the vertical distance between the high point of lesser trochanter and the tear drop line), rotation apex distance (the height between the rotation center of femoral head and the greater trochanter) and rotation tear distance (the vertical distance between the rotation center and the tear drop line) of the three groups. The bilateral distance difference was used as the evaluation index to judge the limb length and eccentricity, and the three groups were statistically analyzed by IBM SPSS statistics 21.0.Results:There was statistical difference in the offset and rotation apex distance between the three groups (P<0.05).There was no significant difference in the p value of large tear distance、small tear distance and rotation tear distance.There was no significant difference in the offset of group1 (P>0.05), but there was significant difference in the offset of group2 and group3 (P<0.05). Group1、group2 and group3 had statistical difference in P value of internal rotation apex distance and small tear distance(P<0.05), while they had no statistical difference in P value of large tear distance and rotation apex distance(P>0.05). Conclusion：Neck-shaft angle has an important effect on limb length and offset.The biomechanical structure of hip joint can be reconstructed well when the difference of bilateral neck-shaft angle is less than 5 degrees.With the reference of the healthy side rotation apex distance, combined neck-shaft angle can provide effective individual guidance for the accurate control of limb length and head and neck distance during hip arthroplasty.