The characteristics of anaerobic degradation of phenol were studied in a fluidized bed reactor using a granular activated carbon as media. Increasing the phenol loading rate with variation of feed concentration was considered as an experimental variable. In the present anaerobic fluidized-bed reactor, the removal efficiency of phenol and COD was maintained about 93-99% and 91-96%, respectively, up to 3.6 kg-phenol/$m^3cdot d$ of the phenol loading rate, but it was abruptly decreased under 5.0 kg-phenol/$m^3cdot d$. The volumetric production of biogas per removed phenol was decreased linearly between 0.80-1.27 m$^3$ gas/kg-phenol (0.35-0.56 m$^3$-gas/kg-COD), increasing the phenol loading rate, and the methane content of biogas was 55-60% as similar to that estimated theoretically up to 3.6 kg-phenol/$m^3cdot d$. But the production rate and methane content of biogas were suddenly decreased at the loading rate of 5.0 kg-phenol/$m^3cdot d$. Therefore, the anaerobically biodegradable phenol loading rate of the present reactor was 3.6 kg-phenol/$m^3cdot$ d in order to accomplish over 90% of the removal efficiency.