Infrared　polarization　technology　is　generally　applied　in　object　detection　and　analysis.　However,　chromatic　aberration　restricted　the　development　of　Infrared　polarization　detectors.　Metalenses　are　two-dimensional　artificial　electromagnetic　materials　to　balance　chromatic　aberration　and　an　ideal　platform　for　miniaturization　and　integration　of　infrared　polarization　technology.　In　this　paper,　a　fully　polarized　detection　of　mid-infrared　achromatic　metalens　is　designed,　with　a　single　metalens　unit　diameter　of　30μm,　a　focal　length　of　15μm,　and　a　working　wavelength　of　3μm-5μm.　Through　FDTD　software　simulation,　the　results　show　that　the　metalens　focuses　at　focal　plane　for　any　polarized　state　light　throughout　the　working　wavelength　band,　with　a　full　width　at　half　maximum　(FWHM)　of　the　peak　of　less　than　6μm,　achieving　achromaticity.　The　maximum　aspect　ratio　of　the　nanopillar　is　15:1,　meeting　the　requirements　of　electron　beam　lithography　processing.　The　designed　metalens　achieves　full-polarization　detection　a　wider　working　wavelength　band　comparing　with　existing　polarization　detection　devices,　which　indicates　a　potential　application　value　for　mid-infrared　polarization　detection　and　imaging　technology.　©　2023　SPIE.　All　rights　reserved.