Objective To investigate the relationship between intraoperative decreases in systolic blood pressure (SBP) and postoperative acute ischemic stroke in advanced age patients (≥75 years) with stroke history. Methods Advanced age patients with previous stroke who were admitted to Xuanwu Hospital, Capital Medical University from January 2019 to April 2022 and underwent non‑cardiac surgery under anesthesia were selected. Patients who presented postoperative acute ischemic stroke before discharge were set as a patient group, while those without postoperative acute ischemic stroke were set as a control group. The patient group (n=24) and the control group (n=96) were matched according to the age and operation method at a ratio of 1∶4. Then, their preoperative, intraoperative and postoperative data were collected from electronic medical records and anesthesia recording system. The maximum intraoperative decreases in systolic blood pressure (SBP) and the minimum SBP were calculated. Both groups were compared for demographic information and potential confounding factors. Conditional logistic regression was used to analyze the relationship between intraoperative decreases in SBP and postoperative acute ischemic stroke. Results There were no significant differences in demographic information or potential confounding factors between the two groups (P>0.05). The patient group showed lower percentages of the maximum intraoperative decreases in SBP less than 10% baseline and between 10% and 20% baseline than the control group (P<0.05), and higher percentages of the maximum intraoperative decreases in SBP more than 20% baseline than the control group (P<0.05). Compared with the control group, in‑hospital mortality and expenses significantly increased in the patient group (P<0.05). Compared with the maximum intraoperative decreases in SBP less than 10% baseline, the maximum intraoperative decreases in SBP more than 20% baseline might significantly increase the risk of postoperative acute ischemic stroke ［odd ratio (OR) 11.909 (95% CI 1.992, 71.212), P=0.007］. Compared with the minimum SBP>120 mmHg (1 mmHg=0.133 kPa), the minimum intraoperative SBP between 100 mmHg and 120 mmHg might obviously increase the risk of postoperative acute ischemic stroke ［OR 3.769 (95%CI 1.186, 11.975), P=0.025］. Conclusions Postoperative acute ischemic stroke can obviously increase in‑hospital mortality and expenses in advanced age patients with previous stroke. Both the maximum decreases in SBP more than 20% baseline and the minimum SBP between 100 mmHg and 120 mmHg can significantly increase the risk of postoperative acute ischemic stroke.