Objective To systematically evaluate the difference in leg length discrepancy (LLD) between robot-assisted total hip arthroplasty (THA) and traditional THA. Methods The Cochrane Library, PubMed, Web of Science, EMbase, CNKI, Wanfang, VIP, and CBM databases were searched by computer to collect cohort studies of robot-assisted and traditional THAs from inception to August 11th, 2021. Two researchers independently screened the literature, extracted the data, and evaluated the risk of bias of the included studies. Meta-analysis was performed using RevMan 5.3 software. ResultsA total of 10 high-quality cohort studies were included. The results of Meta-analysis showed that compared with traditional THA, LLD after robot-assisted THA was smaller [MD=−1.64, 95%CI (−2.25, −1.04), P<0.001], Harris scores at 3 and 12 months after operation were higher [MD=1.50, 95%CI (0.44, 2.57), P=0.006; MD=7.60, 95%CI (2.51, 12.68), P=0.003]. However, the operative time was longer [MD=8.36, 95%CI (4.56, 12.17), P<0.000 1], and the postoperative acetabular anteversion angle was larger [MD=1.91, 95%CI (1.43, 2.40), P<0.001]. There was no significant difference in Harris score at 6 months, amnesia index (Forgotten joint score, FJS), postoperative acetabular abduction angle, and incidence of complication between the two groups (P>0.05). Conclusion Robot-assisted THA is superior to traditional THA in postoperative LLD.