A piling machine with high-pressure jet spiral bit, including an underpan, a pile frame, a drill pipe, a drill bit having an upper leaf helix, a lower leaf helix and a middle leaf helix, a power system, a high-pressure concrete casting system and a high-pressure jet grouting system. The drill bit is disposed at the head of the drill pipe and has multiple nozzles disposed thereon, a diameter of the middle leaf helix is constant from the top to the bottom thereof, a diameter of each of the upper leaf helix and the lower leaf helix decreases from the top to the bottom thereof so that the drill bit with upper and lower tines is formed, the drill bit is spiral, the high-pressure jet grouting system is disposed in the drill bit, and the nozzles are disposed on the drill bit. A piling method is also taught herein.