To counter the problem of difficult digging and low production efficiency of hard cohesive soil in the dredging project, we carry out the cutting test of the original soil, for which the hard clay soil sample needs to be produced. In view of the characteristics of the hard clay, we develop a “vacuum+stack loading” technology for vacuum pumping at the bottom of the dredged silt with high moisture content and high compressibility. The experimental research shows that:1)The preparation device works well, the standard penetration number of clay soil produced is 13 hits, the liquidity index reaches 0.36,the dredging geotechnical engineering level is 4,and the properties are close to the sticky soil which is difficult for construction in dredging project, thus it provides qualified model soil quality for the hard clay cutting test.2)There is a good correlation for moisture content Wand unconfined compressive strength R ,standard penetration number N ,soil bearing capacity Fof preparation soil, the regression coefficients are all above 0.72.The results provide the basic technical support for the researches on the disposal of soft silt in the state of flow plastic.