Objective To study whether the human bone marrow mesenchymal stem cells (HBMSCs) can repair damaged neural cells induced by okadaic acid (OA).Methods Neuroblastoma cell line SH-SY5Y cells were used to incubate with 20nmol/L okadaic acid for 24h,establishing Alzheimer's Disease cell model;Three groups were set up:normal group,okadaic acid-damaged (OA-damaged) group,hBMSCs-treatment group.The cells were injured for 24h with 20nmol/L OA in OA-damaged group,and treated with conditioned medium obtaining hBMSCs for 24h after 24h OA injury in the treatment group.Then CCK-8 was used for detecting cell vitality,immune fluorescence dyed microtubules and micro filaments for determining the dendritic cell length and fluorescence intensity,in addition,Western blotting for analyzing the protein level of phosphorylated tau and total tau proteins.Results Okadaic acid damaged SH-SY5Y cells,contributed to shrinkage,collapse,cavitation of the SH-SY5Y cell body,dendritic shortening and fracture,and irregular arrangement of microtubule microfilaments;while BMSCs conditioned medium made SHSYSY cell body become round and longer,dendrites restored,and microtubules and microfilaments arranged regularly,fluorescence intensity enhanced.Meanwhile,it also down-regulated the level of OA-induced tau phosphorylation.Conclusion hBMSCs have repair effects on the neural cell damage induced by okadaic acid.