Abstract: Preparation technology of activated carbon from rice husk cracking was optimized by combined using Plackett－Burman design，steepest ascent design，and Box-Behnken design.Plackett-Burman design was applied to identify NaOH concentrations，liquid ratio and calcined time as the most significant of 6 factors influencing the iodine absorption value.The center points of the three factors were determined based on steepest ascent design.The optimization of three factors was carried out by using Box-Behnken design.Results showed that the optimal conditions were as follows:NaOH concentration was 2.50 mol/L，reaction time was 60 min，mass ratio of material to liquid was 1.125，calcined time was 37.5 min，and calcined temperature was 600 ℃.Under these conditions，the analogy computing iodine absorption value was 807.76 mg/g.The average relative error was 0.283％ according to reliability experiment.In conclusion，the optimized process was feasible.

Key words: rice husk, activated carbon, Plackett-Burman design, technology optimization