Aim To investigate the application value of 128-slice spiral CT perfusion imaging （CTPI） in the diagnosis of acute cerebral infarction and the evaluation of patients prognosis. Methods Nonenhancement CT and CTPI were performed on 67 patients with acute cerebral infarction within 24 hours who were hospitalized in the People’s Hospital of Gansu Province. Cerebral blood volume （CBV）, cerebral blood flow （CBF） and mean transit time （MTT） of infarction area were obtained. American National Institute of Health stroke scale （NIHSS） scores from each patient were obtained when their conditions became stable in 7 days. Then statistical analysis was made for the correlation between these data. Results 38 cases had been found showing early signs of cerebral infarction by CT scan, and the sensitivity was 56.72%. 56 cases had been found appearing brain perfusion abnormality area by CTPI, and the sensitivity was 83.58%.