A 3D SiO2/carbon nanocomposite is fabricated from lichens successfully. By acid‐washing, nanoporous structure can be generated by removing inorganic compounds. Comparing with the SiO2/carbon nanocomposite before acid‐washing, the one after acid‐washing displays decreased electrochemical reaction resistance and better electrochemical performance as anode materials for the lithium‐ion battery. At a current density of 100 mA g−1, the hierarchical porous SiO2/carbon nanocomposite after acid‐washing shows excellent cycle stability. A high reversible capacity of 583.3 mAh g−1 can still be obtained after 100 cycles, which is much higher than the theoretical capacity of graphite.