Objective To analyze the relationship between levels of serum microRNA-34a (mi-34a) and silent information regulator 1 (Sirt1) and stability of carotid atherosclerotic plaque in elderly patients with cerebral infarction. Methods 102 elderly patients with cerebral infarction admitted to the hospital from February 2018 to February 2019 were enrolled as cerebral infarction group. 50 healthy subjects who were admitted to the hospital for physical examination at the same period were selected as control group. They were given carotid ultrasonography, and were divided into plaque formation group and nonplaque formation group (including unstable plaque group and stable plaque group). The levels of serum mir-34a and Sirt1 were measured among each group. Results The serum mir34a level in cerebral infarction group was significantly higher than that in control group, while the serum Sirt1 level was significantly lower than that in control group (P＜0.05). The serum mir34a level in plaque formation group was significantly higher than that in nonplaque formation group while the serum Sirt1 level was significantly lower than that in nonplaque formation group (P＜0.05). The AUC value, sensitivity and specificity of serum mir34a level in predicting plaque formation were 0.913, 82.90% and 85.70%. The AUC value, sensitivity and specificity of serum Sirt1 level in predicting plaque formation were 0.874, 71.40% and 91.50%. The serum mir-34a level in unstable plaque group was significantly higher than that in stable plaque group while the serum Sirt1 level was significantly lower than that in stable plaque group (P＜0.05). The AUC value, sensitivity and specificity of serum mir-34a level in predicting plaque stability were 0.767, 51.00% and 90.90%. The AUC value, sensitivity and specificity of serum Sirt1 in predicting plaque stability were 0.756, 57.60% and 87.80%. Conclusion The abnormal levels of serum mir34a and Sirt1 are closely related to the formation and stability of carotid atherosclerotic plaque in patients with cerebral infarction, and they can be used as early warning indicators of cerebral infarction.