The objective of this work was to use corncob as raw material to prepare green reusable magnetic biochar for removal of dyes in wastewater. For this purpose, an environmentally friendly NiAl layered double oxides modified magnetic corncob biochar (MC/NiAl-LDO) was obtained by pyrolysis of NiAl layered double hydroxides modified magnetic corncob biochar (MC/NiAl-LDH) at 700 °C for 3 h. The surface area of MC/NiAl-LDO is 552.62 m·g, which was much higher than that of MC (26.83 m·g). MC/NiAl-LDO for acridine orange (AO) exhibited higher adsorption ability, the adsorption capacity of MC/NiAl-LDO was increased by 90% compared with MC. Adsorption experiments for AO on MC/NiAl-LDO were carried with effect of pH, adsorption time, initial concentrations of AO and ionic strength. MC/NiAl-LDO can be recycled nine times. The results exhibited that MC/NiAl-LDO was a low cost adsorbent, providing good example for th agricultural waste recycling.