As the cell size of uncooled infrared (IR) detectors progressively shrinks, it becomes increasingly important to increase detector absorption. here, an IMIAM (Insulator-Metal-Insulator-Air-Metal) cavity type metasurface uncooled IR detector structure is proposed, which effectively improves the uniformity of the photosensitive layer while enhancing the absorption of the detector. Utilizing systematic simulation and optimization, it has achieved almost perfect absorption in the Long Wavelength Infrared range (8~14um), meanwhile, it also shows excellent absorption performance in Mid Wavelength Infrared band. In this paper, the reliability of the structure is also verified by the process. this research may provide alternatives for optimizing conventional uncooled IR detectors.