Abstract: Bentonite and graphite, as fine as powder, are pressed into large, high-density blocks that require super-tonnage loading equipment. For solving this problem, the Two-step compaction method is proposed, that is, the fine powder particles are first pressed into high dense blocks, and then broken into clusters. The aggregates are then remixed with the powder particles and pressed into larger high-density blocks at lower loads. The results show that the "two-step compaction" method can realize the preparation of high-density bulk bentonite by low tonnage press. Pure powder compacted to effective dry density of 1.85g /cm3, the maximum compaction load 14 MPa; For the aggregate - powder mixture, the maximum compaction load is only required 10 MPa. Is it reduced 28.6%. Moreover, the compacted block has good apparent shape and uniform density. When the proportion of aggregates is 10-50%, it is easier to compact. During the compaction process, the granules undergo changes of "rearrangement, fragmentation, and densification". When the mixture ratio between granules and powder is appropriate, a compacted block with localized individual large pores can be formed. Through water absorption expansion and creep adjustment, these large pores are transformed into tiny pores, effectively ensuring impermeability performance.