A portable variable-diameter pile sleeve device for pile driving is provided with a pile sleeve device body mounted on a hammer sleeve of a pile driving hammer, wherein the pile sleeve device body comprises a central round pipe, an annular plate sleeving the central round pipe, a plurality of guide plates mounted on the periphery of the annular plate, annular plate reinforcing plates and lifting lug reinforcing plates; and the annular plate reinforcing plates and the lifting lug reinforcing plates are mounted on the annular plate. The portable variable-diameter pile sleeve device for pile driving can be connected and mounted quickly, safely and efficiently and solves problems in offshore pile driving operation of steel piles and drill conductors of different diameters. Besides, the portable variable-diameter pile sleeve device for pile driving can be used for driving large-diameter steel piles, greatly reduces the production cost and increases the construction efficiency.