The invention relates to the technical field of pile foundation construction, in particular to a double-core drilling tool with three blades. The double-core drilling tool comprises blades, a spindle,I-shaped standing columns, and pulling plates. The spindle includes an inner core tube and an outer core tube. The blades are distributed uniformly along the axis at which the spindle is located; oneend of each blade is connected with the side wall surface of the spindle and the other end is connected with the bottom of one I-shaped standing column; and the pulling plates are inserted into grooves formed in the two sides of the I-shaped standing columns and slide up and down along the grooves. The drilling tool is able to clean drilling cuttings and can adapt to various rock structural formations; the drilling head replacing frequency during screw drilling is reduced; and the drilling efficiency is improved.