Background: High Ki-67 expression is associated with poor prognosis in early-stage lung adenocarcinoma (LUAD). However, there are few studies on the associations between clinicopathological features and Ki-67 proliferation index (PI). The study aimed to explore the clinicopathological characteristics of peripheral clinical stage IA LUAD with high Ki-67 expression. Methods: A case-control study was carried out in China-Japan Friendship Hospital from January 2017 to December 2018. The clinicopathological features of patients were reviewed. Univariate and multivariate analyses were used to analyze the association between clinicopathological characteristics and high Ki-67 expression. Results: Three hundred and seventy-six patients were finally enrolled in the study. Univariate and multivariate analyses showed that males sex (OR =2.23, 95% CI: 1.30-3.83, P=0.004), carcinoembryonic antigen (CEA) positivity (OR =3.25, 95% Cl: 1.44-7.33, P=0.005), several imaging features such as notch positivity (OR =2.55, 95% CI: 1.18-5.51, P4.017), vascular convergence (OR =3.04, 95% CI: 1.03-8.95, P=0.044), and consolidation/tumor ratio (CTR) (OR =1.03, 95% CI: 1.02-1.04, P<0.001) were significantly associated with high Ki-67 expression. The area under curve of receiver operating characteristic (ROC) curve for CTR was 0.813 (95% CI: 0.768-0.858, P<0.001). When cutoff value was 72.5%, the sensitivity and specificity were 80.5% and 76.3%, respectively. Conclusions: Male sex, CEA positivity, notch positivity, vascular convergence, and CTR were significantly associated with high Ki-67 expression in patients with peripheral clinical stage IA LUAD. These findings could be used to assist clinical decision-making and prognostic evaluation.