Abstract: Objective To study gastrodia elata blume to effect tau protein,SOD,MDA expression in gyrus hippocampi and cerebral cortex of experimental mice.Methods To inject okadaic acid to mice ventriculus lateralis and to measure tau protein level,SOD activity and lipid superoxide MDA content of SOD control group,OA injection group,OA and gastio dia elatainjection solution group.Results Tau protein of experimental group(P<0.05/P>0.05),SOD was lower than model group(P<0.001)and was higher than control group(P<0.05).Conclusion Gastrodia elata blume can increase SOD activity and reduce tau pro tein expression and superoxide lipid forming in brain tissue of exper imental dementia mice caused by OA.It can prevent and treat AD.