Porous　hydrogel　incorporated　with　the　photothermal　conversion　materials　has　been　the　key　component　of　the　interfacial　solar　evaporation　device.　However,　the　preparation　of　high-performance　porous　hydrogel　for　the　interfacial　solar　evaporation　device　still　existed　some　limitation,　like　the　widely　available　and　cheap　photothermal　conversion　material,　the　ease　and　scalability　of　porous　structure　construction　in　the　hydrogel.　In　this　work,　a　porous　biomass-derived　hydrogel　evaporator　with　interconnected　pore　structure　were　developed　via　the　simple　and　effective　foaming-freezing-crosslinking　three-step　method　using　sodium　alginate　and　poly(vinyl　alcohol)　as　matrix　materials　and　commercial　graphite　as　the　photothermal　material.　It　has　excellent　photothermal　conversion　and　water　transport　capabilities,　with　an　evaporation　rate　of　3.15　kg　m-2h-　1　and　an　evaporation　efficiency　of　91　%　at　a　solar　irradiation　intensity　of　1　kW　m-　2.　The　evaporator　also　has　excellent　salt　rejection　performance　due　to　its　unique　porosity.　The　evaporator　shows　good　stability　and　long-term　durability　when　evaporating　in　brine　cycles.　This　easily　prepared,　inexpensive　and　biocompatible　hydrogel　evaporator　has　great　potential　in　the　field　of　solar　desalination.