In this paper,a self assembled impedance immune sensor was constructed to detect trace Tau protein in order to achieve the purpose of early diagnosis on Alzheimer disease.The sensor was constructed and characterized by the following steps:the bifunctional molecule 3,3′ dithiobis(sulfosuccinimidylpropionate) (DTSSP) was modified on the gold electrode surface through the Au-S bond,which was then conjugated with antibodies 39E10 through the CO-NH.Tau protein was specifically captured by physisorption using immunoassay,characterized by AC impedance and verified by cyclic voltammetry.By optimizing the DTSSP modification time and antibody concentration,the sensor had a detection signal toward Tau protein of 002-100 μg/mL,in which there existed a good linearity(r2=0988 8) in the concentration range of 02-20 μg/mL with a detection limit of 043 nmol/L.This immunosensors specific capture ability for Tau could be used as a supplementary means for clinical detection on AD.