Alzheimer disease (AD) is a progressive neurodegenerative disease characterized by progressive cognitive and memory decline. Amyloid precursor protein (APP) is a transmembrane protein, it has been known to play an important role in AD pathogenesis. Previous studies have shown that a Chinese herb Futokadsura stem can selectively inhibit the expression of amyloid precursor protein (APP) gene. We want to find the effective components in Futokadsura stem which have the inhibitory effect. Futokadsura stem was separated and purified with chemical methods, and then different separation components were added on SK-N-SH cells in different concentrations. Using MTT methods, we detected proliferation activity of SK-N-SH cells which were treated with different separation components of Futokadsura stem. Using RT-PCR, Western blot methods, we detected APP gene expression in SK-N-SH cells after they are treated with different Futokadsura stem separation components. We found that piperlonguminine/dihydropiperlonguminine components (1:0.8) separated from Futokadsura stem acetic ether extracts could selectively inhibit the expression of APP gene in SK-N-SH cells in mRNA and protein levels. This inhibition effect is concentration-dependent. Under experimental concentrations, the components did not affect the proliferation activity of SK-N-SH cells. These data suggest that piperlonguminine/dihydropiperlonguminine components are the effective components in Futokadsura stem which can inhibit the expression of APP gene.