Objective To investigate the correlations of the formation and stable classification of carotid atherosclerotic plaque with triglyceride (TG)/high-density lipoprotein cholesterol (HDL-C) ratio and small and dense low-density lipoprotein cholesterol (sdLDL-C) in the elderly people with normal low-density lipoprotein cholesterol (LDL-C) level. Methods General and serological data of the elderly people with age≥65 years old and LDL-C＜3.40 mmol/L, who came to our hospital from May 2021 to May 2022, were retrospectively analyzed. According to the presence or absence of carotid plaque, the patients were divided into non-plaque group (57 cases) and plaque group (131 cases). According to the results of ultrasonic superb micro-vascular imaging (SMI), the plaque group was further divided into neovascularization group (unstable plaque group, 77 cases) and non-neovascularization group (stable plaque group, 54 cases). To further analyze the serological risk factors of carotid atherosclerotic plaque formation and neovascularization in plaque, SMI grading was conducted for neovascularization in plaque. Results TG/HDL-C ratio and HDL-C and sdLDL-C levels were significantly different among the non-plaque group, neovascularization group and non-neovascularization group (all P＜0.05). In the plaque group, the plaque thickness and sdLDL-C level of patients with SMI grade 0, SMI grade 1 and SMI grade 2 increased in turn, and the differences among the 3 SMI grades were statistically significant (both P＜0.01). Spearman rank correlation analysis showed positive correlations of SMI grade of carotid plaque with plaque thickness and sdLDL-C level in the elderly people with normal LDL-C level (r＝0.758, P＜0.01; r＝0.676, P＜0.05). When the plaque thickness, sdLDL-C, HDL-C and TG/HDL-C ratio were used as independent variables and the plaque SMI grade was used as a dependent variable for linear regression analysis, the results showed that plaque thickness and sdLDL-C were risk factors for plaque SMI grade (b＝0.779, P＜0.001; b＝0.436, P＜0.05). Conclusion HDL-C, TG/HDL-C ratio and sdLDL-C are related to the formation of carotid plaque in the elderly people with normal LDL-C level. Plaque thickness and sdLDL-C level are risk factors for neovascularization and plaque stability.