This study constructs a metal-semiconductor-metal photodetector based on a hexagonal gold nanowire structure for enhancing the light absorption capability and responsivity of photodetectors at specific wavelengths. An tin indium oxide layer, which exhibiting excellent optical transparency and electrical conductivity, is coated onto this structure. Multiple models are established using the finite element simulation software COMSOL to conduct comparative simulations. Following parameter optimization, the overall light absorptivity of the device reaches 90% in the wavelength range of 700?1500 nm. The responsivity of device reaches 0.39 A/W under a bias voltage of 5 V and an incident light power of 10 mW. Furthermore, the thickness of GaAs layer, diameter of hexagonal gold nanowires, and angle of incident light affect the performance of the device.