The invention discloses a lift-off pile foundation structure for a soft soil foundation, and belongs to the technical field of pile foundations. The lift-off pile foundation structure comprises a shell, wherein a reinforcing mechanism is arranged in the shell; and the outer side of the shell is provided with an outer cover ion a sleeved mode, the upper surface of the outer cover is fixedly connected with a positioning mechanism, and the positioning mechanism is detachably connected to the outer side of the shell. According to the lift-off pile foundation structure for the soft soil foundation,by arranging the reinforcing mechanism, when a supporting column is hammered, the supporting column moves downwards and drives a triangular block to move downwards, at the moment, the triangular block extrudes a sliding block, the sliding block is extruded to drive one ends of first inserting rods to move, the first inserting rods move in first sliding sleeves, at the moment, the first insertingrods can be inserted into soil, meanwhile, when a hemisphere block at the upper portion moves downwards, two hemisphere blocks get close to each other, at the moment, the hemisphere blocks can extrudesteel balls, the steel balls can move after being extruded, at the moment, the steel balls can drive second inserting rods to move, and meanwhile, the plurality of second inserting rods can be inserted into the soil, so that the shell is reinforced, and then a pile foundation is stabler during fixing.