The utility model discloses a load box fixing structure for a pile foundation self-balancing static load test. The load box fixing structure is characterized in that a load box is fixed in a limiting support in a surrounding mode, the limiting support comprises a plurality of vertical reinforcing steel bars evenly distributed on the load box in the circumferential direction and two horizontal annular bars, the middles of the vertical reinforcing steel bars are provided with protruding limiting sections matched with the load box, the two horizontal annular bars and the inner sides of the vertical reinforcing steel bars are welded, one of the two horizontal annular bars is located above the protruding limiting sections, the other one of the two horizontal annular bars is located below the protruding limiting sections, the upper portions of the vertical reinforcing steel bars and the lower end of upper-section steel reinforcement cage main reinforcement is connected through lap joint welding lines, and the lower portions of the vertical reinforcing steel bars and the upper end of lower-section steel reinforcement cage main reinforcement are connected through lap joint welding lines. By means of the load box fixing structure, the load box can be kept at the set position all the time without skewing in the test process, it is guaranteed that loads can be correctly applied, and the load box fixing structure is convenient to construct.