Abstract: The application of dual-purpose piles is a technique in which retaining piles are combined with outer walls of substructures to resist the earth pressure. The application of dual-purpose piles in topdown construction can save costs and make the mechanical condition of substructure walls more rational. Based on a real construction, ANSYS is used to calculate the mechanical features of the combination of retaining piles and substructure walls during different construction stages. The mechanical features of the combination of retaining piles and substructure walls during different construction stages are calculated. The results show this design can provide good economic benefit, which is a desirable reference for similar construction .