The flexible pile clusters are widely used in the renovation engineering of the passenger wharf and old wharves to solve the problem of ship berthing，but the stipulations in the code concerning the ship impact can’t satisfy the requirement of the pile’s maximum displacement.This paper discusses the pile internal force and deformation of the berthing pile cluster structure under the action of ship impact forces from multiple angles，and suggests to calculate the maximal displacement of piles and internal force within the ship impact force angle within the scope of 70°～80° during the design process to meet the operation requirements of the structure and to provide some valuable reference for the structural design and calculation，safe use and reliability evaluation for the berthing pile cluster structure.