The invention relates to the technical field of bridge construction, in particular to a structure of a pier pile foundation and a construction method thereof. The structure of the pier pile foundationcomprises a precast bearing platform and precast pipe piles. The precast bearing platform is arranged above the precast pipe piles, the bearing platform is provided with central hole passages and peripheral hole passages, and the peripheral hole passages are arranged on the periphery of the central hole passages. The peripheral hole passages are internally provided with positioning steel bars. The structure of the pier pile foundation and the construction method thereof have the beneficial effects that through the arrangement of the positioning fixed steel bars and positioning steel plates, the precast bearing platform can be connected with the precast pipe piles through mechanical structures during the installation process, fixing is convenient, the construction time is saved, and meanwhile, the safety in the construction process is enhanced; meanwhile, the positioning steel bars can provide better horizontal shear resistance, the relative stability between the pier pile foundation and the precast bearing platform is enhanced to avoid relative sliding between the pier pile foundation and the precast bearing platform; and the arrangement of the fixed steel bars can effectively strengthen the connection between the precast pipe piles and cast-in-place concrete.