Surface plasmons are collective oscillations of surface electrons in metal, as well as the related electro-magnetic fields, which are induced by incident lights. So far, the spectral characteristics of the surface plasmons of gold micro-nano particles have been widely studied and applied, at the visible light regime. In addition, the spectral properties in the mid-infrared wavelength region have also drawn great attention in the community, due to its great potential in the research of good-quality sensors. So far, to systematically adjust the paramters including the resonance wavelength, the maximum absorptance and the full width at half maximum intensity, etc. in the design of the surface plasmon-based photoelectric sensing devices, is still a key issue in the community. Compared with single paticles, array-based structures possess great advantages in tuning the above mentioned parameters due to the characteristics of periodicity. Therefore, in this work, an array structure based on gold micro-nano particles is proposed. With the finite difference time domain method, the reflectance spectrum, transmittance spectrum and absorptance spectrum in a wavelength range of 4～18 μm are systematically studied, by varying the structural parameters of the gold array including the particle radius, the particle height, the particle separation, and the particle shape. The results in this work reveal a resonance characteristics within the wavelength range of 8~10 μm that occurs when the incident light resonates with the induced surface plasmons of the gold micro-nano array. The results also indicate that the resonance wavelength, the absorptance peak intensity and the full width at half maximum intensity of the resonance spectrum can effectively be adjusted by tuning the structural parameters of the gold array. Based on the spectral characteristics demonstrated in this work, the proposed gold micro-nano array structure may be utilized in the future design of photoelectric sensors at the mid-infrared wavelength regime.