Abstract: Objective: To evaluate the value of spectral CT with optimal monochromatic energy to improve the CTA image quality of head and neck. Methods: A total of 60 patients with suspected head and neck vascular diseases admitted to our hospital from February 2016 to December 2017 were selected for subtraction spectral CTA of neck and neck. Two subtraction images of the optimal monochromatic energy and conventional mixed energy were obtained, and arterial attenuation of the aortic arch, the end of the common carotid artery and the M1 segment of the middle cerebral artery were measured, and the two groups of signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated; the subjective quality score of the two groups were evaluated; The differences between the two groups were compared. Results: The mean attenuation values of the optimal monochromatic energy group and the conventional mixed energy group were 445.25±105.45 and 283.88±71.96 in the aortic arch, and the mean attenuation values were 444.00±96.02 and 350.38±76.40 at the end of the common carotid artery, and the mean attenuation values were 375.00±73.78 and 280.00±55.12 in the M1 segment of the middle cerebral artery, and there were significant differences among the three of them. The SNR of the two groups were 62.01±39.56 and 31.36±17.35, and the CNR were 60.46±39.19 and 30.10±16.80, respectively; and there were significant differences among the two of them, and there were significant differences in the subjective quality score of the two groups of images. Conclusion: The spectral CT with optimal monochromatic energy subtraction CTA is better than the conventional mixed energy subtraction CTA. It has higher arterial attenuation, SNR, CNR, and subjective quality score, which can improve the image quality of head and neck angiography and optimize the display of arteries.