The clinical data of 73 symptomatic patients with chronic internal carotid artery occlusion (CICAO) who underwent endovascular therapy in the Second Affiliated Hospital of Soochow University and Suzhou Ninth People's Hospital from January 2011 to May 2019 were retrospectively analyzed, and the related factors of successful endovascular therapy were determined. The patients were divided into recanalization group (49 cases) and non-recanalization group (24 cases). The related factors of successful endovascular recanalization in patients with symptomatic CICAO were investigated by both univariate and multivariate logistic regression analyses. The results showed that distal ICA reconstitution at the clinoid segment (=8.946, 95%: 1.782-44.910) and tapered stump (=4.488, 95%: 1.147-17.566) were related factors of successful endovascular therapy in patients with CICAO (both <0.05). However, calcification at the beginning of occluded ICA (=0.161, 95%: 0.027-0.965) was an adverse factor for successful endovascular therapy in patients with CICAO (<0.05). This study indicates that the related factors of successful ICA endovascular therapy in patients with symptomatic CICAO mainly include tapered stump and distal ICA reconstitution at the clinoid segment, while calcification at the beginning of occluded ICA was an adverse factor.