Objective To explore the clinical application of superb micro-vascular imaging (SMI) in evaluating the role of Banxia Baizhu Tianma decoction in improving the stability of carotid atherosclerotic plaque of hypertension with phlegm dampness obstruction. Methods A total of 120 patients with carotid atherosclerotic plaque of hypertension with phlegm dampness obstruction were enrolled, they visited the First Affiliated Hospital of Heilongjiang University of Chinese Medicine from Sep. 2018 to Sep. 2020. The patients were randomly divided into control group and treatment group (60 cases in each group). The control group was treated with atorvastatin calcium tablets, 20 mg once a day, orally after breakfast; the treatment group was also treated with Banxia Baizhu Tianma decoction, 50 watered pills each time, twice a day, orally after meals. Both groups were treated for 6 months. The serum levels of low-density lipoprotein-cholesterol (LDL-C), total cholesterol (TC) and triglyceride (TG) were recorded before and after treatment. Routine ultrasound and SMI were performed. Carotid intima-media thickness (IMT), carotid plaque Crouse score and carotid plaque SMI grade were observed before and after treatment. Results There were no significant differences in serum levels of LDL-C, TC or TG between the 2 groups before treatment (all P>0.05); the serum levels of LDL-C, TC and TG in the 2 groups were significantly lower after treatment than those before treatment (all P<0.05); and the serum levels of LDL-C, TC and TG in the treatment group were significantly lower than those in the control group after treatment (all P<0.05). There were no significant differences in carotid IMT or plaque Crouse score between the 2 groups before treatment (both P>0.05); the carotid IMT and plaque Crouse scores of the 2 groups were decreased after treatment, with no significant difference (both P>0.05); there were no significant differences in carotid IMT or plaque Crouse score between the 2 groups after treatment (both P>0.05). There was no significant difference in carotid plaque SMI grade between the 2 groups before treatment (P>0.05); after treatment, the proportions of patients with carotid plaque SMI grade 2 were decreased and those with SMI grade 0 were increased in both groups compared with those before treatment (both P<0.01), and the proportion of patients with carotid plaque SMI grade 2 in the treatment group was significantly lower than that in the control group (P<0.05). Conclusion SMI can be used to evaluate the role of Banxia Baizhu Tianma decoction in improving the stability of carotid atherosclerotic plaque of hypertension with phlegm dampness obstruction, which can help to evaluate the clinical effect of medication.