The present invention provides siRNA, peptide oligonucleotide drugs, and their applications for suppressing the expression of the amyloid precursor protein (APP) gene in human cells. The siRNA exhibits potent activity in inhibiting APP expression. Through appropriate modifications, its ability to silence the target is enhanced while reducing off-target activity. The described siRNA and its conjugates hold promise for clinical application in the prevention and treatment of diseases associated with the APP target, including cerebral amyloid angiopathy (CAA), early-onset familial Alzheimer's disease (EOFAD), or Alzheimer's disease (AD).