Abstract: Activated carbons were modified by microwave of 4 different powers at different time in high purity nitrogen ambient.Pore structure and microstructure of both conventional and modified activated carbons were tested by the (apparatus) of N2 adsorption and X-ray analysis.Effect of microwave treatment on pore structure of activated carbon was studied by comparing conventional and modified activated carbons.Results showed that microwave treatment of activated carbon resulted in insignificant change of surface area,decreased mesopore,basically unvaried micropore volume and enlarged microcrystallinity.