Abstract: Objective To explore blood biomarkers in the early stage of acute cerebral infarction using iTRAQ technology. Methods Forty patients with acute cerebral infarction admitted in Zhoushan Hospital of Zhejiang Province from July 2016 to July 2018 were selected and divided into 5 groups according to the onset time: cerebral infarction group 1(onset<2 h), group 2(onset 2 to 4 h), group 3(onset 4 to 6 h), group 4(onset 6 to 24 h), and group 5(onset 24 to 72 h), with 8 cases in each group. There were another 3 groups: transient cerebral ischemic attack group(onset<2 h), acute cerebral hemorrhage group(onset<2 h), and the control group, with 8 cases in each group. The iTRAQ technique was used to detect the serum and screen out clinically significant biomarkers. Results ① Multiple differential proteins were found in the acute phase of cerebral infarction, mainly involved in 165 biological processes, 35 cellular components, and 38 molecular functions. ② These differential proteins mainly involve 3 types of biological metabolic pathways: complement regulation pathway, blood coagulation pathway and cell signal transduction pathway. Cell components included extracellular space, platelet a particle, lipoprotein complex, and secretory granules. Molecular functions included enzyme activity, ionics, etc. ③ The unique biomarkers of cerebral infarction included actin, cytoplasmic 1, serum amyloid P-component, properdin, C-reactive protein, serum amyloid A-1 protein, glyceraldehyde-3-phosphate dehydrogenase. Actin and cytoplasmic 1 were the most meaningful. Conclusion The tight blood-brain barrier tight junction damage within 2 h of acute cerebral infarction is a characteristic change, which can effectively distinguish acute cerebral infarction with transient ischemic attack and cerebral hemorrhage. Actin and cytoplasmic 1 may be a specific marker that can be used for acute cerebral infarction.