Abstract: This paper discussed the changes in the static triaxial strength of silty clay and clay mixed with lime, cement and fly-ash at different mixture ratio. The relationship between mixture ratio and strength of different mixtures was obtained through analysis and comparison.Such results could provide a reliable guideline for design, construction and maintenance of the subsoil to assure the requirements be met for the subgrade bed of high speed railway and embankment fillings below the subgrade bed.