In this paper, a self-powered near-infrared photodetector was fabricated based on a single-walled CNT (SWCNT) /graphene/GaAs double heterojunction structure. Due to the excellent photoelectric properties of GaAs and high carrier mobility of graphene, the photodetector exhibits a high photoresponsivity, detectivity and the on/off ratio of 393.8mA/W, 6.48×1011Jones and 103, respectively. More importantly, combing the near-infrared light absorption of SWCNTs with the photo-generated carriers effectively separated by the SWCNT/graphene heterojunction, the spectral response of the double heterojunction device is broadened to 1064nm, breaking through the absorption limit of GaAs itself.