Abstract: The technology conditions for preparation of active carbon from rice hull by steam activation and the factors influencing the activation were investigated.The result showed that the optimum conditions were the carbonization temperature 450℃, the activation temperature 900℃, the activation time 90 min and steam to solid ratio 1.5:1.The maximum adsorbing ability of the active carbon for iodine is 844 mg/g, for methylene blue is 138 mL/g and its yield is 13.9%.These indexes are equal to those of activated carbons made from woods. The advantage of the technology is less in energy consumption and investment,therefore,it has better economic and social benefits.