The invention relates to a pre-hole-forming stiff composite tree root pile construction process. According to a pre-hole-forming stiff composite tree root pile, hole forming is performed in advance ina soil layer through a rotary drilling rig, meanwhile, soil outgoing is performed through a drill bit, till a counter bore achieves a needed depth, after hole forming detection is qualified, single or a plurality of prefabricated components with barbs or cast-in-place steel pipe piles are placed in, then cement mortar perfusion is performed, vibrating compacting is performed so that cement mortarand the prefabricated components or the cast-in-place steel pipe piles are fully fused, and the pre-hole-forming stiff composite tree root pile is formed. The pre-hole-forming stiff composite tree root pile construction process has the advantages that soil extruding is free during pile forming, the construction speed is high, all pile bases in a single bearing table can be completed at a time, the bearing force is large, rigidity is large, cost is low, benefits are high, energy saving and environment protecting are achieved, and wide application in the fields of industrial and civil construction, municipal construction and the like is achieved.