Background and Aims There is currently no definitive clinical consensus regarding the treatment of metachronous liver metastasis after radical resection of pancreatic ductal adenocarcinoma (PDAC). Therefore, this study was performed to compare the efficacy of liver resection (LR) and microwave ablation (MWA) for the treatment of metachronous hepatic oligometastasis following PDAC resection in order to provide reference guidelines for the clinical management of these patients.Methods The clinicopathologic data of 74 patients with metachronous hepatic oligometastasis after PDAC radical resection, treated between January 2014 and December 2021 at Meishan People's Hospital, were retrospectively collected. Among them, 37 patients underwent LR (LR group), 28 patients received MWA (MWA group), and 9 patients received only palliative chemotherapy (conservative treatment group, compared with the former two groups for survival benefits). Based on clinical follow-up data, the postoperative complications and long-term efficacy were compared between the LR and MWA groups, and risk factors for the long-term efficacy of PDAC patients were analyzed.Results There were no statistically significant differences in baseline characteristics between the LR and MWA groups (all P>0.05). The median overall survival (OS) in the LR and MWA groups was 25.0 months (95% CI=21.5-28.5) and 23.0 months (95% CI=19.2-26.8), respectively, while the conservative treatment group had a median OS of 11.0 months (95% CI=8.9-13.1). The median progression-free survival (PFS) in the LR and MWA groups was 17.0 months (95% CI=14.7-19.3) and 15.0 months (95% CI=11.7-18.3), respectively. Survival curve comparisons showed no statistically significant differences in OS rate and PFS rate between the LR and MWA groups (χ²=0.184, P=0.668; χ²=0.488, P=0.485). There was no statistically significant difference in recurrence rate between the two groups (70.3% vs. 78.6%, χ²=0.569, P=0.451), but the LR group had a significantly higher incidence of severe postoperative complications compared to the MWA group (48.6% vs. 14.3%, χ²=8.405, P=0.004). The LR group also had a significantly longer hospital stay than that of the MWA group (9.0 d vs. 5.0 d, P<0.001). Cox multivariate regression analysis indicated that perioperative chemotherapy omission and early liver metastasis (<1 year) were independent risk factors for poor prognosis in PDAC patients (both P<0.05).Conclusion LR and MWA are effective treatments for metachronous liver metastasis after PDAC resection, with similar long-term efficacy. However, MWA is associated with fewer severe postoperative complications and shorter hospital stays. Poor prognosis is observed in PDAC patients who do not receive perioperative chemotherapy and experience early liver metastasis (<1 year).