An amperometric biosensor for H2O2 detection was developed with immobilization of Horseradish Peroxidase (HRP) on Ag nanowires (AgNWs). Ag nanowires (AgNWs) have been prepared by the reductive deposition method and characterized by the scanning electron microscopy (SEM) and the energy dispersive X-ray (EDX). The electrochemical performance of the HRP/AgNWs/GC electrode was investigated by cyclic voltammetry (CV) and chronoamperometry and the use of Ag nanowires led to an efficient enzyme loading, and also provided an increased surface area for sensing the reaction, showing high electrocatalytic activity towards the reduction of H2O2. Under the optimized conditions, the response of the biosensor towards H2O2 was investigated by chronoamperometry. The biosensor exhibited excellent sensitivity (the detection limit was down to 0.005 mM), fast response time (15 sec). Moreover, the biosensor had long-time stability and good reproducibility.