Objective To evaluate the clinical value of CT perfusion (CTP) imaging in assessing the thrombolysis window for acute cerebral infarction (ACI). Methods A total of 64 patients with ACI admitted to the Department of Radiology, Xuchang Municipal Hospital, between January 2023 and December 2024 were prospectively enrolled. All underwent non-contrast CT and CTP within 24 hours of onset, and the diagnosis was confirmed by MRI. Patients were divided into an early-window group ( ≤ 4.5h, n=30) and an extended-window group ( > 4.5h, n=34) according to the actual onset-to-imaging time (OIT). Grouping was performed independently of CTP results to avoid circular reasoning bias. General characteristics, perfusion parameters [cerebral blood ?ow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time-to-peak (TTP)] and ischemic core and penumbra volumes were compared between the two groups. The consistency between CTP judgment and clinical time window was analyzed using the Kappa test, and receiver operating characteristic (ROC) curves were plotted to evaluate diagnostic performance. Radiation dose and key performance indicators（KPIs） for outpatient and emergency services were monitored simultaneously. All patients underwent follow-up after 3 months of treatment, with prognosis assessed using the modi?ed Rankin Scale (mRS). Results No signi?cant differences were found in baseline data between the two groups (P > 0.05). The early- window group showed signi?cantly higher CBF and CBV values but lower MTT and TTP values than the extended- window group (P < 0.05). The ischemic core volume was smaller, whereas the penumbra volume and mismatch ratio were greater (P < 0.05). The overall agreement between CTP assessment and the clinical time window was 90.6%, with a Kappa value of 0.812 (P < 0.05). ROC curve analysis indicated that the mismatch ratio yielded the highest diagnostic accuracy (AUC=0.901), outperforming individual parameters. The mean CTDIvol was (49.2 ± 6.3) mGy and DLP was (820 ± 95) mGy·cm, with an overall success rate of 96.9% and an average turnaround time of approximately 34 minutes, demonstrating both safety and ef?ciency. The 3-month follow-up revealed that favorable outcomes (mRS ≤ 2) were more frequent in the early-window group than those in the extended-window group (73.3% vs. 38.2%, P < 0.05), and patients with a mismatch ratio ≥ 2 had better outcomes than those with a ratio < 2 (P < 0.05). Conclusion Independent OIT-based grouping combined with CTP quantitative analysis provides an objective evaluation of cerebral perfusion across different stages ofACI. CTP demonstrates strong consistency with the clinical time window and high diagnostic value for thrombolysis eligibility. The mismatch ratio offers greater advantages than traditional single parameters. Under low-dose protocols and optimized work?ows, CTP effectively balances imaging quality and timeliness, providing a safe and ef?cient implementation pathway for emergency thrombolysis assessment.