Abstract: A series of porous carbon materials (YAC-x) were prepared from corn stalk using ZnCl₂ as etchant by adjusting their relative dosages. The obtained samples were characterized by XRD, Raman, XPS, TEM and N₂ adsorption-desorption. Furthermore, a three-electrode supercapacitor system was employed to investigate their electrochemical performance. Comparing with the unetched corn stalk-derived carbon (YC), the resultant porous carbon materials have more abundant pore structure and much better supercapacitor performance. Among them, YAC-4 is the most prominent one, whose specific capacitance is as high as 236.8 F/g at a current density of 1 A/g. This is due to its large pore volume (V_p=1.11 cm³/g) and high specific surface area (S_BET=2060 m²/g).