Semi-floating gate field-effect devices based on graphene have been extensively studied due to their nonvolatile memory characteristics. In this paper, a graphene field-effect device with few-layer graphene as the channel, hexagonal boron nitride as the tunnel barrier layer, and graphene as the charge trapping layer is fabricated. Because of its unique semi-floating gate structure, the transfer characteristic curve has double Dirac points, which are systematically studied. At the same time, we get the stable retention characteristics of the device. Within 200 s, the device program and erase current ratio can be maintained at about 20 μA. Our research is helpful realizing two-dimensional optoelectronic devices based on the semi-floating structure.