A root-like expandable foundation pile is disclosed. It includes a movable drill, a foundation body, a number of foundation blade, a foundation cap and a stopper. The foundation blades are designed to have the warped portion protruding outward, so that they can expand outward by rotating the root-like expandable foundation pile in a direction different from that makes the root-like expandable foundation pile drilled into the soil. Extra bearing capacity can be available from the expanded foundation blades. Time and cost of installation can both be saved.