[Objective] To investigate the influence of body composition on outcome of unicompartmental knee arthroplasty by metaanalysis.[Methods] The literatures from CNKI, Wanfang, Weipu, China Biomedical Literature Database, PubMed, Embase, Cochrane Li-brary and Web of Science were searched by computer untill September 2023, and meta-analysis of the included literatures was performedusing RevMan 5.4. [Results] A total of 11 literatures were included, including 3 prospective studies and 8 retrospective studies, all ofwhich were high quality studies, involving a total of 3 624 knees, including 1 258 knees in the obese group and 2 366 knees in the normalgroup. As results of meta-analysis, there were no statistically significant differences in VAS score, KSS score, HSS score and incidence ofpostoperative complications between the obese group and the normal group (P＞0.05). However, the obese group was marked significantlylower postoperative OKS score (I2= 89%, MD=-2.99, 95%CI -5.18~0.81, P=0.007), and significantly less postoperative knee range of mo-tion (I2=34%, MD=-3.38, 95%CI -4.32~-2.44, P＜0.001), whereas significantly higher postoperative revision rate (I2= 23%, RR=1.51, 95%CI 1.06~2.14, P=0.02) than the normal group. [Conclusion] Compared with those normal body composition, the obese patients do still ob-tain benefits from UKA, but with postoperative OKS score and knee joint motion inferior to the normal body composition patients, while in-creased postoperative revision surgery rate.