A pile driving barge comprises a barge body, buoyancy adjusting devices are arranged at four corners of the barge body respectively, an upper scanner and a lower scanner for scanning vertical piles are arranged on the barge body, and GPS signal receivers are arranged at two different positions of the barge body; anchor machines for anchoring at least four different positions are arranged on the barge body; a pile frame is rotationally arranged on the barge body; the barge body is provided with an automatic pile frame lying device; a piling guide rail is arranged on the pile frame; a pile hammer is movably arranged on the pile driving guide rail; a first brake device for limiting the position of the pile hammer on the pile driving guide rail is arranged on the pile hammer, a transition roller is arranged on the upper portion of the pile frame, the upper portion of the pile hammer is connected with a winch arranged on the barge body through a steel wire rope, and a second brake device for braking by braking a winch roller to control the steel wire rope to pull the pile hammer is arranged on the barge body; and a pile cap is arranged on the pile hammer, a pile gripper for gripping thevertical pile is arranged on the lower portion of the pile frame. The invention further discloses a posture adjusting method, a positioning control method and a pile driving method of the pile driving barge.