Objective: To analyze the feasibility of using vascular plaque quantification (VPQ) to evaluate carotid atherosclerotic plaques and to observe the effect of statins on carotid atherosclerotic plaques. Methods: Patients with carotid plaques from January 2016 to September 2018 in Peking University First Hospital Neurology Department were recruited and underwent three-dimonsional ultrasound (3DUS). Their gray scale median (GSM) and other parameters of carotid plaques were measured with VPQ. The patients were divided into low GSM group (GSM < 40) and high GSM group (GSM≥40). The clinical characteristics and plaque characteristics of the patients in the two groups were compared to analyze the stability of plaques. According to whether taking statins or not, the patients were further divided into statin group and non-statin group, plaque GSM and other parameters of their carotid plaques were measured and the changes of carotid plaques at the end of 3 months and 2 years were observed. Results: A total of 120 patients were enrolled, including 79 males and 41 females, with an average age of (65.39±9.11) years. The patients were divided into low GSM group (31 cases) (GSM < 40) and high GSM group (89 cases) (GSM≥40). The stenosis of the lumen in the low GSM group was more severe (the area stenosis rate was 41.32%±21.37% vs. 29.79%±17.16%, P < 0.05). The nor-malized wall index (NWI) of plaque in low GSM group was significantly higher than that in high GSM group (0.61 ±0.14 vs. 0.52±0.12, P < 0.01). A total of 77 patients, including 51 males and 26 females, aged (64.96±9.58) years, were enrolled to observe the statin effects on carotid plaque. They were divided into statin group (n=56) and non-statin group (n=21) according to whether taking statins or not. At the baseline and 3-month follow-up, there were no significant differences in carotid plaque volume, area, degree of luminal stenosis and GSM between the two groups (P>0.05). At the end of the 2-year follow-up, GSM increased in the statin group [median 10.00 (2.00, 28.00)] but decreased in the non-statin group [median －7.00 (－11.00, 5.50)], with a statistically significant difference between the two groups (P < 0.01). There was no significant increase in carotid plaque volume in the statin group, while there was a slight increase in the non-statin group, but there was no significant difference between the two groups [median increase in plaque volume was 0.00 (－30.00, 40.00) mm³ in the statin group and 30.00 (10.00, 70.00) mm³ in the non-statin group, P>0.05]. Conclusion: The VPQ technology of 3DUS can be used to evaluate carotid atherosclerotic plaques. Patients with low GSM (GSM < 40) have more severe vascular stenosis and higher normalized wall index. VPQ technology can also be used to observe the effect of statins on carotid plaque, the GSM of plaques increase in patients who are taking moderate-intensity statin treatment for two years.