To analyze the structural characteristics of intestinal microflora and changes of serum inflammatory factors of the Alzheimer’s disease, and to explore the relationship between them and dementia, we selected 30 patients in the AD group and 30 patients in the normal group, and collected stool samples to analyze the intestinal flora structure characteristics of the two groups of patients, and statistically analyzed the inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-8 by ELISA from the venous blood of the two groups. The gene discussed is TNF; the disease is early-onset autosomal dominant Alzheimer disease.