The population of early-onset Alzheimer's disease (EOAD) accounts for 1%-2% of the total population of Alzheimer's disease, and genetic mutations are more common in EOAD. The first symptom of the patient in the present case report was the decline in memories of recent events, and the disease progressed rapidly in the following 2 years. Genetic testing has revealed the presence of genetic mutations (c.A479G, p.N160S) of ACE, which causes the 160th codon of the ACE protein to change from aspartic acid to serine, and at the same time genotype of apolipoprotein E (APOE) is ɛ3/ɛ4. We think that this patient carries the mutation type of the sensitive gene ACE and the risk gene APOE of Alzheimer's disease, and this is the reason why the disease progressed rapidly. Moreover, we discussed ACE genetic mutation's meaning in EOAD progression.