Objective To study the effect of selecting the craniocerebral artery with severe internal carotid artery as the input artery on the CT perfusion imaging parameters of the brain. Methods A total of 72 patients with severe internal carotid artery stenosis and abnormal brain CT perfusion were selected retrospectively. The side of internal carotid artery stenosis (experimental group) and contralateral middle cerebral artery (control group) were selected as input arteries for brain CT perfusion, and the results of the two groups were compared and analyzed. We objectively compared the peak features of the input arteries of the two groups and the differences in the resulting perfusion parameters, and subjectively evaluated the difference in the area of the abnormal perfusion area and the pseudo-color scale of the two groups. In this paper, SPSS 22.0 software was used to perform paired t test or paired rank sum test on objective data. Results There was no statistically significant difference between the two groups in the input arterial enhancement peak, peak time and relative value of perfusion parameters (all P>0.05). Only the difference in absolute value of CBFpatients, MTTpatients and MTThealthy was statistically significant (P<0.05). The results of the experimental group and control group were as follows: CBFpatients: (11.61±4.83) and (10.94±4.34) mL/100 g/min, MTTpatients: (14.17±2.51) and (14.7±2.23) s, MTThealthy: (7.91±1.49) and (8.45±1.38) s. In addition, the color scales of CBF, TTP and MTT were different among the three patients with different input arteries, but they did not affect the interpretation of abnormal perfusion area. Conclusion In patients with severe internal carotid artery stenosis, the selection of the cranial cranial artery as the input artery will not affect the determination of abnormal areas of craniocerebral perfusion.