Objective To assess the feasibility of the “double- low” CT angiography - low-kilovolt and low contrast agent dose in cerebral and neck angiography. Methods In this study, low contrast agent dose-35ml would be used in cerebral and neck CT angiography. Twenty patients, clinically suspected the insufficiency of head-and-neck artery, were divided into two groups. One group (10 patients)took the conventional tube voltage-120KV,while the other group(10 patients)took the 80KV tube voltage, both the amount of contrast agent were 35ml, and the injection rate was 5ml/s, then injected 40ml saline with the same rate. Both of two groups take auto- Care dose 4D and Safire reconstruction, according to the original images and Maximum intensity projection(MIP), comparing the display of the vessels in cerebral and neck , calculating the radiation dose, and the density, noise, signal-to-noise ratio, contrast-to-noise ratio of the parenchymal with different kilovolts, then take statistical analysis. Results The qualities of the images to both of the groups respectively are 5.833±0.100 and 5.856±0.133, P=0.694>0.05; Noise of the images respectively is 2.261±0.026 and 2.522±0.031,P=0.000<0.05, the noise is markedly increased; The radiation doses are 412.4±49.2 and 101.8±11.6, P=0.000<0.05, the radiation doses are dramatic declined. Conclusion With the use of “double-low” in dual-energy CT in cerebral and neck angiography, not only ensuring the images could be used to the clinical diagnose, but also reducing the radiation dose and the contrast agent dosage; In cerebral and neck angiography, it is hopefully used in the screening and reexamination during therapy, and it is worthy of further study and application.