Abstract: Drawing the experiences of mechanism of reinforcing clay-soil foundation in the sand drain method, the present paper puts forward a method in which the saturated silty clay foundation is reinforced by dynamical sand-soil piles. Loading testing research on proving zone of a practical project has showed that not only the sand piles have high density and strength, but also have physical and mechanical properties of ground soil been significantly improved. Bearing capacity of composite ground has been greatly enhanced. Application of the method to the project also proves the testing results .