Solar steam generation (SSG) is a novel technique for addressing water scarcity and seawater desalination. SSG converts solar energy into thermal energy via photothermal material, and the thermal energy is then utilized to enable the vaporization of saline water transported to the surface of the photothermal material. Polymers have unique advantages in SSG, such as their highly porous structure could facilitate effective water transport, their lightweight makes them able to float on water, and their light scattering and absorption properties ensured their high energy conversion efficiency. In this chapter, the basic knowledge, design principles, key factors, characterization methods, and structural optimization approaches of porous polymer-based SSGs will be covered.