Addressing the issues of large size, complex optical systems, and limited detection bands in traditional polarization navigation sensors, this study conducts the design and performance analysis of a UV-visible dual-band metalens for Stokes polarization detection. Inspired by the polarization-sensitive mechanism of the monarch butterfly′s compound eye, we systematically analyze the polarization sensitivity in the dorsal rim area of lepidopteran compound eyes and propose a metalens capable of Stokes detection in the ultraviolet to visible range. By employing dielectric elliptical nanopillars to introduce propagation phase modulation across both UV and visible bands, the device biomimetically replicates the polarization resolution capability of microvillar arrays in compound ommatidia. Each metasurface unit enables parallel detection and resolution of Stokes parameters by independently controlling the phase response of incident polarized light along two orthogonal directions. The metalens design is optimized through FDTD simulations, and its performance is evaluated by analyzing the DoLP and AoP under various incident polarization angles. Simulation results demonstrate that the metalens achieves an average transmittance of 90% across the ultraviolet-visible band, with a maximum focusing efficiency of 84%. The DoLP under varying incident polarization angles ranges from 0.91 to 0.98, while the overall AoP error remains below 2°. In terms of fabrication and experimental validation, this study employs micro-nano fabrication processes such as magnetron sputtering, electron-beam lithography, and plasma etching to fabricate metalens samples and carries out practical measurement and evaluation of their Stokes-parameter detection performance. Experimental results demonstrate minimum average relative errors of 1.7% for DoLP and 12% for AoP under partially polarized states. This work presents a novel optical-device design strategy for ultraviolet-visible dual-band polarimetric detection, while simultaneously offering a pivotal technical pathway toward the miniaturization and integration of polarization-based navigation systems.