Abstract: Objective: To investigate olanzapine's protective effect on death of double transfected（Swedish APP gene and presenilin1 gene） N2a cells induced by β-amyloid peptide（Aβ）. Methods: Double transfected N2a cells were treated with olanzapine or/and Aβ.The MTT assay was used to determine cell viability,BCA assay to determine the protein content of cells,and the（Enzyme）-Linked-Immuno-Sorbent Assay（ELISA） to determine the intracellular and extrocellular levels of Aβ produced by double transfected N2a cells. Results: The olanzapine had protective effect on transfected N2a cell death induced by Aβ.The extracellullar Aβ of cells treated with olanzapine decreased significantly comparing to the vehicle（P＜0.05）;the intracellular Aβ did not change significantly（P＞0.05）. Conclution: This data suggest that olanzapine can decrease the production of β-amyloid peptide 42 in double transfected N2a cells and clinically may be helpful in protecting neuron and slowing down the progression of AD by this means.