Objective: To investigate the effect of interaction between serum uric acid (UA) level and carotid intima-media thickness (IMT) on carotid plaque in elderly patients with hypertension. Methods: A total of 133 hypertensive patients were retrospectively analyzed, and the patients were grouped according to the presence or absence of carotid plaque. The clinical data of patients in the plaque group and the non-plaque group were compared, and the influencing factors of carotid plaque formation were analyzed by Logistic regression. The interaction of serum UA level with IMT and its effect on carotid plaque in elderly patients with hypertension were analyzed. Results: Age, IMT, UA, and low-density lipoprotein cholesterol (LDL-C) in the plaque group were higher than those in the non-plaque group (P < 0.05). The results of multivariate analysis showed that age, UA, LDL-C, and IMT were all influencing factors on the formation of carotid plaque in elderly patients with hypertension (P < 0.05). The area under the curve (AUC) of serum UA level in the diagnosis of carotid plaque was 0.838 (95% CI: 0.764–0.896), with a sensitivity of 73.26% and specificity of 82.98%, indicating certain diagnostic value for carotid plaque formation. There was an additive interaction between UA level and IMT, and the risk of carotid plaque formation was higher when high UA level and increased IMT were present simultaneously than when either factor was present alone (RERI = 1.71, 95% CI: 0.22–3.41). The synergistic effect was 1.60 times the sum of the effects produced by the two factors alone (SI = 1.60, 95% CI: 1.12–2.35). Conclusion: Both high serum UA levels and increased IMT are independent risk factors for carotid plaque formation in elderly patients with hypertension, and they exhibit an additive interaction effect. Their simultaneous presence leads to a significantly higher risk of carotid plaque formation.