The invention discloses a wile-drilling sand washing, pressure testing and draining integrated device which comprises a barrel and a sliding sleeve plunger. The sliding sleeve plunger is sleeved withthe barrel; a radial oil drainage hole is formed in the barrel; the sliding sleeve plunger is temporarily fixed on the barrel through a cut-off dowel and meanwhile, the sliding sleeve plunger which istemporarily fixed blocks the oil drainage hole temporarily. Two sealing slots are separately formed on the upper and lower sides of the outer wall of the sliding sleeve plunger, and an O-shaped sealing ring is mounted in each of the sealing slots, so that the outer wall of the sliding sleeve plunger and the inner wall of the barrel are sealed. A plunger through hole is formed in the center of thesliding sleeve plunger in a penetrating mode, and the inner walls of the upper and lower ports of the sliding sleeve plunger are designed as inner conical surfaces, so that steel balls can be in position conveniently. The device disclosed by the invention integrates three processes: sand washing, pressure testing and draining, and guarantees normal while-drilling pressure testing work targets oftubular columns of different types and different well deflections.