Abstract: In order to perceive the relationship between strength and sand content of soils stabilized by cement mortar and find out the useful formula for engineering applications,the characteristics of strength and deformation of soils stabilized by cement mortar and the influences of sand content and age were studied through unconfined compression tests.It was indicated that the strength of cement-treated soils was greatly improved through mixing of some sands;there was a best sand content when the cement content was fixed,and the deformation coefficient(E50) and the unconfined compressive strength(qu) were the greatest under the best sand content;there was a peak value in the stress-strain curves of soils stabilized by cement mortar,and the type of stress-strain curves was strain softening,the residual strength increased with the increasie of sand content;when the cement mortar mixed-in-place piles were used to improve soft soils,the geostatic stress in composite ground and additional stress in underlying layers increased a little even though the sand content and displacement ratio were considerable.