Objective To compare the postoperative outcome and alignment correction of two kinds of unicompartmental knee arthroplasty (fixed-bearing and mobile-bearing). Methods From September 2016 to September 2019，a retrospective study was conducted on 60 patients who had a unicompartmental knee arthroplasty in our hospital, allotted into fixed-bearing group and mobile-bearing group according to the kind of prostheses (30 cases per group). Knee Society Score system (KSS), The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Oxford knee score (OXFORD-12) were used to evaluate the postoperative recovery of pain and range of motion of knees. The hip-knee-ankle angle (HKA) and femorotibial angle (FTA) were used to evaluate the correction of alignment postoperative. Results There was no significant difference in operation time, blood loss, incision length, time of beginning walking and hospital stay between the two groups. The postoperative KSS, WOMAC and OXFORD scores of two groups were significantly improved compared with which before surgery(P＜0.05). Postoperative WOMAC and OXFORD scores of the fixed-bearing group were higher than those of the mobile-bearing group(P＜0.05). The postoperative correction of HKA and FTA of mobile-bearing group was significantly greater than that of fixed-bearing group(P＜0.05). Conclusion Mobile-bearing UKA and Fixed-bearing UKA are both capable of lessening pain and improving function of anteromedial knee osteoarthritis. Two prostheses have no significant difference from the perspective of function. Fixed-bearing UKA has a better subjective feeling in the early postoperative period and mobile-bearing UKA has a larger correction of alignment.