Modern design of novel materials has been more and more prone to integration, so as to implement multi-functions via compatible design. In this work, a single-layer multispectral metasurface (MM) is designed to achieve multispectral compatibility between microwave and infrared. For microwave, a polarization rotator is designed and analyzed to achieve broadband cross-polarization rotation. And for infrared, Genetic Algorithm (GA) is employed to increase the metallic filling ratio, so as to reduce the infrared emissivity without affecting polarization rotation bandwidth of microwave. As a validation, the single-layer MM is fabricated and measured, and the results show that it has achieved polarization rotation in 3.5-5.8 GHz with an efficiency of over 90%, and meanwhile, the infrared mean emissivity has been reduced to 0.25 in 3-14 mu m. More importantly, the single-layer MM and the design method have a promising future in multi-functional integration and multispectral stealth technology.