Since presently Alzheimer's disease (AD) is incurable, early diagnosis of AD is crucial. Aβ 1-42 and tau-441 proteins are promising core biomarkers for early diagnosis and early therapeutic intervention in AD. Here we constructed a surface-enhanced Raman spectroscopy (SERS) biosensor for highly sensitive quantitative detection of Aβ 1-42 and tau proteins by preparing gold nanocube (AuNC) superlattices through evaporation self-assembly. The results showed that the method has a wide response range (0.1-10 000 ng mL-1 and 0.01-1000 ng mL-1, respectively) and high sensitivity. The detection limits of Aβ1-42 and tau protein were 0.0416 ng mL-1 and 0.0087 ng mL-1, respectively. In addition, the method was able to rapidly and simultaneously detect the two biomarkers in serum, which showed the feasibility of the method in complex biological environments. The detection of Aβ 1-42 and tau protein has great potential for the accurate prediction and early diagnosis of Alzheimer's disease.