The invention provides a drilling device of a pre-drilling type lateral pressure test. The drilling device comprises a
cutting ring soil miller, a spoon-type
drill, a
drill bit, a locator, drilling rods, outer rods, a connecting rod and a baffle. A hole forming method for carrying out the pre-drilling type lateral pressure test through the device comprises the steps that 1, an instrument is assembled, wherein the
drill bit and the wall of the spoon-type drill are connected, the wall of the spoon-type drill is connected with the connecting rod, and the connecting rod is connected with the drilling rods; 2, drilling is carried out, wherein drilling is stopped when the locator is in contact with the ground surface, the center of the
cutting ring soil miller is aligned to the locator to be vertically pressed into the underground, the baffle is arranged on the corresponding outer rod at the upper end of the
cutting ring soil miller, and the cutting ring soil miller is vertically pressed into soil by pressing the baffle through the gravity of a drilling
machine or hammering the baffle through a heavy hammer; 3, testing is carried out; and 4, drilling continues to be carried out, and the lateral pressure test of different depths in the same drilled hole is carried out. The device is simple in structure, detachable, convenient to manufacture and maintain, safe, stable, easy to operate, low in manufacturing cost, high in drilling speed and high in hole forming quality, the construction period can be remarkably shortened, and the
adverse effect of hole collapse and hole shrinkage to the result of the lateral pressure test is eliminated.