Abstract: As the pixel size of the vanadium oxide (VO_x) uncooled infrared focal plane decreased, the absorption area of the detector exhibited a sharp quadratic decrease in the edge length. Improving the absorption efficiency of the VO_x uncooled infrared focal plane arrays has become a crucial research topic. In this study, a comprehensive and systematic simulation of the factors affecting the optical absorption of single-layer and double-layer VO_x uncooled detectors was conducted from the aspects of material and structure, in terms of the absorption characteristics of single-layer material, different absorption structures, height of the cavity, and thickness of the film system. A systematic approach to improve the absorption of VO_x uncooled detectors is provided by quantitatively comparing the factors with the simulation results, which have certain reference significance for the design and research of VO_x uncooled detectors.