Abstract: One new curing agent,which uses low-grade diatomite,phosphogypsum,carbide slag as raw materials,used for shield slurry treatment was developed. It can solve the resource utilization of solid wastes and shield slurry in the same time. The difference modification methods affect on the pozzolanic activity of low-grade diatomite was analyzed. The optimal ratio of curing agent was obtained through mixture experiments. The unconfined compressive strength tests and scanning electron microscope(SEM)tests on both new solidified soil and lime-flyash solidified soil were carried out. The microscopic mechanism of the solidified soil was breif discussed. The results show that the best of pozzolanic activity of diatomite is under 15 mins mechanical grinding and 2 hours thermal activation with 500 degrees. The optimal ratio of the new curing agent is modified diatomite: phosphogypsum: carbide slag=0.39:0.23:0.38. The 28 days strength of the new solidified soil is about 7.31 MPa,which is nearly about 2.7 times of that of lime-flyash solidified soils. The strength of the solidified soil was formed by the interweaving of soil particles and pozzolanic reaction products,such as Ca(OH)₂ crystals,calcium silicate hydrate(C-S-H),ettringite(AFt),et al.,and its structure gradually became dense and stable with the increase of the curing age.