The utility model belongs to the technical field of geotechnical engineering. A small-size double-circular-hole drilling tool comprises a first drill bit, a second drill bit, a gear box and a drillingrod, the first drill bit and the second drill bit do not collide with each other when rotating respectively, and intersected double circular holes are drilled; the gearbox comprises an input shaft, afirst output shaft and a second output shaft, the first drill bit is connected with the first output shaft, the second drill bit is connected with the second output shaft, and the drill rod is connected with the input shaft. The drilling tool is good in double-round-hole drilling effect and high in efficiency.