Objective To investigate the influence of three methods of tibial rotation osteotomy on the position parameters and clinical function of tibial prosthesis in Oxford unicompartmental arthroplasty.Methods From January 2018 to June 2020, 59 patients with medial compartment osteoarthritis of the knee were selected, including 35 males and 24 females, 31 cases ( left knee )and 28 cases(f right knee). According to the number method, they were randomly divided into three groups, observation group A used anterior superior iliac , observation group B used medial intercondylar crest tip and patellar tendon tibial tubercle insertion line(substitute anteroposterior line，sAP) , observation group C used tibial anatomical axis. The incidence of polyethylene liner protrusion, tibial external rotation angle, varus angle and posterior inclination angle, and KSS score of knee joint were observed.Results (1) in the observation group A, 5 cases (26.32%) of the polyethylene liner moved forward medial process, the average distance was 2.07 ± 0.52mm. In the observation group B, there were 2 cases (10.00%), the average distance was 1.93 ± 0.38mm (X2 = 6.553, P = 0.037). (2) The external rotation angle of observation group A was 7.84 ± 2.49 degrees, which was significantly higher than that of observation group B and C (3.79 ± 0.71 degrees and 4.02 ± 0.67 degrees, P < 0.001). There was no significant difference between observation group B and C (P > 0.05). (3) The average follow-up time was 9.82 ± 2.05 months. There was no dislocation or loosening during the follow-up period. In observation group A, there were 5 patients with polyethylene liner protruding and 3 patients with pain. There was no significant difference in the clinical scores before and 1 month after operation among the three groups (P > 0.05). 6 months after operation, the difference between the two groups was statistically significant (P < 0.001).Conclusions In Oxford unicompartmental arthroplasty, the external rotation of tibial prosthesis is located by sAP line and tibial anatomical axis, which is easy to operate and has high repeatability, and is conducive to the recovery of joint function after operation.