The invention discloses a pile body static test device and a support leg bottom ground reinforcing method. The pile body static test device comprises a soft soil area, a test pile, a jack, a support and a heavy object; the test pile is inserted into the soft soil area, the jack is arranged at the upper end of the test pile, the heavy object is arranged on the support, and support legs of the support are located on the two sides of the test pile. The pile body static test device is characterized in that a pit is formed in the corresponding support leg of the soft soil area, geotechnical cloth is arranged on both the inner wall of the pit and the top surface of the pit, the geotechnical cloth is filled with a filler containing water absorption particles, the geotechnical cloth is used for sealing the bag opening after being filled with the filler, a base plate is laid on the upper surface of the pit, and the support legs are supported on the base plate. According to the support frame, the support legs of the support can be effectively prevented from sinking into the soft soil, and meanwhile, the support can be prevented from inclining, so that the support can be well kept in a horizontal state, and therefore the experimental result is more accurate.