Photodetectors are widely used in communication, detection, medical and other fields. With the development of industries such as aerospace, night vision, remote sensing, thermal imaging, automotive interconnection and consumer electronics, the demand for ultra-wideband photodetectors is increasing. Existing ultrawide band detectors are multiple photodetectors using different materials and different detection bands, which are poorly integrated and restrict the development of the above applications. We design a graphene micron strip-metal grating composite structure photodetector. It provides a photoelectric response in the terahertz, infrared and visible spectral regions. In the visible region, the metal grating significantly increased the detection sensitivity from 1.1 mA/W to 2.5 mA/W. This work provides new ideas for the design of graphene-based ultra-wideband photodetectors.