A precast segment suitable for block-stacking concept is disclosed. The precast segment includes a first surface, an opposite second surface, plural through holes, and plural male-female connecting sets. The through holes extend from the first surface and toward the second surface to communicate between the first surface and the second surface. Each male-female connecting set includes a shear key and a joint hole, wherein the shear key protrudes from one of the first surface and the second surface to serve as a male connecting unit, and the joint hole is formed in the other of the first surface and the second surface to serve as a female connecting unit. Accordingly, the precast segments can be block-stacked by mortise-and-tenon joints to construct a bridge pier system. Compared to the conventional construction methodology, the present invention can enhance the efficiency of segment fabrication and avoid high prestress force.