Objective    To construct the highly alpha-fetoprotein (AFP) sensitive immunosensor based on multi-wall carbon nanotubes-prussian blue-chitosan (MWNTs-PB-CHIT) nanocomposite and protein A (PA) using indium tin oxides (ITO) electrode.     Methods     Nano-Au was electrically deposited on the surface of ITO electrode. MWNTs-PB-CHIT nanocomposite was dropped onto the ITO electrode surface modified by gold nanoparticles. PA on the composite surface was adsorbed through the electrostatic and chitosan force with negative charge for immobilizing AFP antibodies at pH 6.5.     Results    The peak current value of the immunosensor was linearly related with the AFP at a concentration of 1.0 to 250.0 ng/ml level with a detection limit of 0.5 ng/ml. The response time of stable current was 6 min and the RSD of the current was less than 3%.     Conclusion     The new immunosensor we constructed is economical and disposable.