Objective: To systematically evaluate the efficacy of surgical and conservative treatment for small-diameter abdominal aortic aneurysm (AAA). Methods: The randomized controlled trails (RCTs) comparing surgical (endovascular aortic repair and open surgery) and conservative treatment for small-diameter AAA were collected by searching the national and international databases. After assessment of methodological quality of the included studies according to the Cochrane Reviewers’ Handbook criteria, Meta-analysis was performed by using RevMan 5.1 software. Results: Four RCTs were finally included, with a total of 3 314 patients, of whom 1 680 cases underwent surgical treatment and 1 634 cases underwent conservative treatment. Results of Meta-analyses showed no significance difference between the two groups of patients in all-cause mortality (SMD=0.97, 95% CI=0.68–1.38), aneurysm-related mortality (SMD=0.81, 95% CI=0.56–1.17), incidence of aneurysm rupture (SMD=0.49, 95% CI=0.09–2.54) and mortality within postoperative 30 d or during hospitalization (SMD=0.88, 95% CI=0.60–1.29) (all P>0.05). Conclusion: In treatment of small-diameter AAA, the outcomes between surgery and conservative treatment are similar. However, the clinical significance of this conclusion is uncertain, and the authors based on comprehensive analysis deem that small-diameter AAA still needs aggressive surgical treatment.