The light harvesting capacity and thermal conductivity properties of photothermal materials play a vital role in the photothermal conversion of solar energy. However, most materials do not possess both of these characteristics simultaneously or efficiently. Here, we design and prepare a composite material with both light harvesting capacity and thermal conductivity properties, which polypyrrole is loaded on the surface of thermal conductivity rod-shaped boron nitride to form h-BN/PPy composites. The composites can be dispersed in a mixed solution of glycol-water and can exist stably. The photothermal conversion efficiency reach 82.84% when the concentration is 0.05 wt%. While combining this composite with PVA-1799 can form a hybrid membrane, which can still exhibits high photothermal conversion performance, and its photothermal conversion efficiency can reach up to 82.05%. And exhibits high stability and corrosion resistance in seawater. Thus may be potentially applied in the solar desalination field.