Abstract: Gypsum-Slag(GS) soil hardening agent is a new type of soil curing material composed of cement,steel slag,mineral slag,desulfurization gypsum and other additives. This study focused on the GS soil hardening agent and cement and carries out a series of laboratory unconfined compressive strength tests and scanning electron microscope tests. Test results include the stabilized soil stress-strain curves and the effects of soil type,the amount of admixture and age on the mechanical properties of stabilized soil as well as its microstructure. The test program also includes a series of field tests designed to verify the laboratory data. The results indicate that the stress-strain curve of GS curing soil has obvious peak value,while that of soil-cement soil is relatively flat. The strength of the both curing soils increase with the increasement of proportion and age. However,the growth of GS curing soil strength is more uniform which is extremely different from cement curing soil. The deformation modulus of GS curing soil is 31.11~77.24 times the compressive strength,while that of cement curing soil is 23.24~71.62. In the field test,the integrity of pile formed by GS hardener is better than that of soil-cement pile. Based on the characteristics of quick increasing strength,high intensity in later period and good economic benefit,the GS agent is competent with cement in soil stabilization in underground,subgrade and other engineering.