Highly sensitive, selective and rapid immunoassays capable of detecting proteins in a multiplexed fashion are essential for disease diagnostics, drug screening and biodefense applications.Herein, a capacitive biosensor based on interdigitated array microelectrodes (IDAMs) was developed for ultrasensitive multiplexed proteins detection by using two kinds of nanoparticles.In this system, magnetic nanoparticles (MNPs) modified probes were used as capturer of antigen and gold nanoparticles (GNPs) functionalized another probes as detector.Then GNPs promoted silver reduction to enhance the electrical signal.Finally, the silver particles bridged the gap of IDAMs and gave a measurable electrical signal determined by capacitive biosensor.Using this method, we have detected two target proteins, ricin and cTnl, at concentrations as low as 0.1 nM.Compared to the bio-barcode amplification assay (BCA), this system was minimized by omitting the procedures of releasing the barcode strands from the gold nanoparticles and making another quantification step.