As the pixel size of the vanadium oxide (VOx) 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 VOx 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 singlelayerand double-layer VOx 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 VOx uncooled detectors is provided by quantitatively comparing the factors with the simulation results, which have certain reference significance for the design and research of VOx uncooled detectors.