Abstract: By adopting gold nanoparticles and BSA- TiO2 antibody, a highly sensitive amperometric immunosensor for the determination of AFP was prepared and was then utilized to link gold nanoparticles （nano-Au）for the immobilization of anti-AFP. The preparing process of the immunosensor was characterized by the cyclic voltammetrys. The results showed that the immunosensor possesses a highly sensitive current response，with a linear range of 0.01~80 ng/mL and a detection limit of 0.003 ng/mL. The preparing method is characterized by easy electrode preparation, simple procedures and high sensitivity which helps fulfil the quantitative analysis of AFP. .