Abstract: Objective To investigate the differences in the etiology between minor stroke and non-minor stroke based on TOAST and ASCO systems, and to guide the early intervention for minor stroke. Methods We retrospectively analyzed the patients with acute ischemic stroke admitted to our department from July 2012 to July 2014. We sub-typed minor stroke patients and non-minor stroke patients in etiology using Trial of Org 10172 in Acute Stroke Treatment （TOAST） and ASCO （A for atherosclerosis, S for small vessel disease, C for Cardiac source, O for other cause） systems respectively to investigate the difference of etiology between the two groups. Results We included a total of 406 patients with minor stroke and 651 patients with non-minor stroke. The constituent ratio of TOAST was different (P<0.001) between the two groups. small-artery occlusion （SAO） was the highest cause (40.4%，164 cases) in minor stroke group, while stroke undertermined etiology （SUE）was the most common (30.9%，201 cases)in non-minor stroke group. The A1+2 ratio and C1+2 ratio in minor stroke group were lower than those in non-minor stroke group (22.8% vs. 35.4%, P<0.001; 19.3% vs. 32.1%, P<0.001), and the ratio of S1+2 was higher than that in non-minor stroke group (49.8% vs. 27.3%, P<0.001). Conclusion The etiology of minor stroke is different to non-minor stroke SAO is the most common cause in minor stroke, while CE and LAA are more common in non-minor stroke.