To study the feasibility of evaluation of collateral channel (CC) classification in patients with coronary chronic total occlusion (CTO) by coronary computed tomography angiography (CTA) with reference to invasive coronary angiography (ICA) validation. We retrospectively included CTO-confirmed patients who underwent both coronary CTA and ICA within 1 month. Collaterals were classified by coronary CTA into three types: CC0, no continuous connection between donor and recipient vessel; CC1, continuous thread-like connection; CC2, continuous, small sidebranch-like connection. With comparison to ICA results, the diagnostic performance of CTA-based CC classification was further assessed. 118 patients with 132 ICA-confirmed CTO lesions were included. Compared to ICA-based evaluation, good overall diagnostic accuracy of CT-based CC classification was observed (78 %, 103/132, κ = 0.674, p < 0.001). Coronary CTA was also revealed to be accurate in terms of assessment of collateral tortuosity (76.2 %, 77/101) and identification of principal donor vessel (70.3 %, 71/101). Impaired diagnostic performance was observed in sub-group of septal collaterals as the accuracy for evaluation of the above parameters was 60.6 % (20/33), 72.7 % (24/33) and 45.5 % (15/33) respectively. Non-invasive evaluation of CC classification by coronary CTA correlates well with ICA findings. In addition, the septal collaterals are much less visible at coronary CTA than epicardial collaterals.