Everywhere in nature we can find wonder designs and systems that never cease to inspire us looking for answers to engineering and design. In this paper, bio-inspired triboelectric nanogenerator (BITENG) has been designed to mimic the motion of kelp, which gently sways along with wave and harness the energy in this process. The energy harvesting has been proven as stable and efficient, which could work under a vibration frequency as low as to 1 Hz. Correspondingly, an output current of about 10 μA and voltage of 260 V can be given by a single unit, which is enough to drive at least 60 LEDs with a power density of 25 μW·cm−2. Furthermore, large scale application can be promoted by connecting such BITENG into network. Such a bio-inspiration provides a new strategy for harvesting wave-energy with promise for new energy sources based on TENGs.