The invention relates to a rotary excavating pile driving mechanism of hydraulic pile driving equipment. The rotary excavating pile driving mechanism comprises a rotary excavating power device, a connecting flange, a spiral drilling rod, a rock breaking drill bit, a drill bushing, an ascending and descending body and a main clamp, wherein the rotary excavating power device is connected with the drill bushing through the connecting flange; the spiral drilling rod is arranged in the drill bushing; the spiral drilling rod is connected with the rock breaking drill bit; the rotary excavating power device drives the spiral drilling rod and the rock breaking drill bit to rotate in the drill bushing; and the drill bushing is fixed on a hydraulic pile driving machine body by the ascending and descending body and the main clamp to do downwards pressing and upwards hoisting actions. The rotary excavating pile driving mechanism achieves the effects that the spiral drilling rod drills into the ground; the rock breaking drill bit breaks rock; great rock is cut off by shearing force between the spiral drilling rod and the drill bushing and is brought out of the ground; sand and stone soil brought out by the spiral drilling rod is discharged out through soil discharging holes of the drill bushing; a steel plate pile is arranged in the main clamp; and the steel plate pile is pressed into the ground when the ascending and descending body performs downward pressing. The rotary excavating pile driving mechanism can be used under the condition of meeting various geological conditions, and solves the problem that the steel plate pile cannot be directly pressed in for construction under some special geological conditions.