Abstract: To solve the adaptability of conventional bored piles and driven piles under coral reef geological conditions, we propose a new type of prefabricated ultra-high-performance concrete (UHPC)-perfusion RC composite pile. Taking the approach of a cross-sea bridge as an example, the combined pile scheme was compared with the original scheme to illustrate the economic and technical advantages of the former. To grasp the force characteristics and the calculation method of the bearing capacity of the connecting section, five groups of push-out tests and finite element analyses were carried out to investigate the influence of the height ratio, number of shear keys and the interfacial adhesion on the bearing capacity and failure mode of the combined key. The reasonable height ratio of composite key teeth, the design process of connecting section and the calculation method of bearing capacity were determined.