Taking a proposed residential building in Ansai District,Yanan as an example,a program of variable stiffness composite foundation is proposed. The variable stiffness composite foundation of half-hard and half-soft rock geological conditions is carried out by numerical simulation with the finite element analysis software MIDAS GTS NX. The settlement characteristics of foundation are studied by changing the design parameters of soil modulus,pile modulus,pile spacing,pile length and so on. The suitability of variable stiffness composite foundation is based on the study of differential settlement. The results show that differential settlement of half-hard and half-soft rock foundation can be solved by the variable stiffness composite foundation. The differential settlement can be controlled within a reasonable range by adjusting the design parameters of variable stiffn ess composite foundation.