Abstract: The buffer material in nuclear waste disposal was made up with pure bentonite or sand-bentonite mixture.The wall friction was induced between the materials and the wall of compaction mold during the compaction process,so it was hard to obtain the relationship between the actual compaction stress and the density of the bentonite block.A series of compaction tests of various L/D ratio were carried out in this study,and the compression equation developed by Gurnham was applied to obtain the friction-free compressive curve of bentonite block.This friction-free compaction curve could eliminate wall friction force and the geometric effect.The effects(stress rate,wall lubrication,crush rock content) that would influence the friction force in compaction procedure were analyzed and discussed.