Granular activated carbon (GAC) is extensively used to remove natural organic matter and residential chlorine in water treatment process of power plant. After being used, the spent GAC needs to be regenerated in order to save on operation costs and reduce solid waste disposal. In this study, microwave technique was tried to regenerate the field-spent GAC from a power plant. The effect of microwave power, irradiation time and hydrochloric acid pretreatment were investigated, it was found that microwave could recover the adsorption capacity of GAC within a short time and the tannic acid adsorption efficiency of regenerated GAC was 9 times greater than spent GAC; hydrochloric acid pretreatment could improve the regeneration process, it showed the highest removal efficiency and iodine number, 99.6% and 859 mg/g respectively. The results obtained from SEM-EDX showed that hydrochloric acid pretreatment could remove inorganic matter and other impurities of GAC. All these indicate that microwave technique can effectively regenerate field-spent GAC, and hydrochloric acid pretreatment is an important process before regeneration.