In this study, a reduced graphene oxide/polyacrylamide (rGO/PAM) three-dimensional (3D) composite hydrogel coupled with current collector graphite brush (GB) was developed as anode for microbial fuel cells (MFCs). The rGO/PAM was fabricated through in-situ polymerization of acrylamide in graphene oxide dispersion, followed by reduction with ascorbic acid. The resulting macro-porous scaffold with high surface area and biocompatibility was benefit for both mass diffusion of the culture medium, microbial colonization and electron mediators. As a result, the GB/rGO/PAM anode produces a remarkably high maximum power density and volumetric power density of 758mWm(-2) and 53Wm(-3) at the stable state of power generation, respectively. Moreover, the orientated rGO/PAM (O-rGO/PAM) with higher conductivity could further improve the maximum power density of MFCs, achieving 782mWm(-2). The above results are substantially higher than those of traditional GB, plain carbon cloth (CC), and the control GB/GO/PAM and CC/rGO/PAM based electrodes measured under the same conditions. The new 3D composite hydrogel electrode shows great promise for improving the power generation of MFCs devices.