Previous studies have explored interfacial solar steam generation (ISSG) for photothermal conversion and seawater purification via biobased solar-driven devices. Nevertheless, as the water transport and solar absorption were inadequate, the seawater purification of current devices is limited. Herein, we report an efficient bamboobased evaporator that demonstrates the torrefaction bamboo and avoids fabrication defects, achieving an excellent evaporation performance of 1.522 kg/m2 h with 94.4% conversion efficiency and sharp response time 80 s under one sun irradiance. This evaporator provides a stable self-floating state with continuous micro-nano channels, which were significantly parallel with the air-water surface, generating more photothermal energy and sharper water molecule movement than current devices. Simultaneously, this bamboo-based evaporator leads effective seawater purification towards the insoluble matter, soluble humus, and organic or inorganic matter, removing 99.58% of dissolved solids with self-clean capacity. Theoretical simulations deepen the synergy between water transport and photothermal location, promising prospects for the future development of highperformance biobased evaporators to ensure clean fuel and freshwater challenges.