Abstract: Solar-driven interfacial water evaporation, as an environmentally friendly, efficient, and sustainable desalination technology, has received extensive attention in recent years. Fast water transport and efficient photothermal conversion performance are the key points to achieve continuous and steady evaporation. Biomass-derived evaporators with multi-level pores demonstrate the potential for efficient, eco-friendly, and sustainable applications in solar water evaporation. A biomass-based evaporator with a natural porous structure was designed from discarded sugarcane knots using freeze-drying and high-temperature carbonization methods, and its light absorption, water transport, and evaporation capabilities were studied. It is reported that convective air with different wind speeds has an improving effect on the evaporation performance and heat loss of the evaporator. The results showed that the biomass-based evaporator with a well-developed microchannel structure had a solar absorption of 92.8%, an evaporation rate of 1.55 kg/(m²·h) and a light-to-heat conversion efficiency of 77.6% under 1 sun. Furthermore, at a wind speed of 2 m/s, the evaporation rate and the photothermal conversion efficiency of the evaporator reached 2.27 kg/(m²·h) and 91.6%, respectively, showing the enhancement of the freshwater yield rate by convective effects and the suppression of heat loss.