Objective To explore the correlation of TOAST and MRI classification with shortterm prognosis of patients with acute cerebral infarction (ACI). Methods The clinical data of 153 patients with ACI admitted to the hospital were retrospectively analyzed between January 2018 and January 2021. The clinical baseline data, serological indicators and National Institutes of Health Stroke Scale (NIHSS) scores of patients with different TOAST types and different MRI types were compared. According to the modified Rankin Scale (mRS) score at 3 months after discharge, the patients were divided into good prognosis group (mRS≤2, n=89) and poor prognosis group (mRS>2, n=64). The correlation of TOAST classification and MRI classification with short term prognosis of patients with ACI was analyzed. Results TOAST classification of the 153 patients showed cardiogenic embolism (CE) in 36 cases, small artery occlusion (SAO) in 42 cases, large artery atherosclerosis (LAA) in 40 cases, other vascular disorders (SOE) in 14 cases, and undetermined cause (SUE) in 21 cases. MRI classification showed large infarction in 20 cases, medium infarction in 31 cases, small infarction in 43 cases, and lacunar infarction in 59 cases. The order of NIHSS score at admission, serum cystatin C (Cys-C), homocysteine (Hcy) and low-density lipoprotein (LDL) levels in patients with different TOAST subtypes from high to low was as follows：large infarction > medium infarction > small infarction > lacunar infarction (P<0.05). The order of the reduction rate of NIHSS score from low to high was as follows：large infarction