Abstract: The measured results of forces at pile top of tube frame structural system and large-scale model tests by applying the optimized design of pile foundation stiffness to reduce differential settlement show that the forces at pile top in different tube areas increase with the increase of loading level, and those under the tube and peripheral frame columns tend to be uniform under the working loads. The optimized design of pile foundation stiffness to reduce differential settlement can adjust distribution of forces and improve stress behavior of rafts. In model tests, the improvement ratio for tubes is in the decreasing order of angle pile, side pile and center pile. The corresponding pile butt force ratio of the forces to mean values is 1.15∶1.02∶0.83. The measured pile forces are in the decreasing order of peripheral frame columns, peripheral frame edge columns and piles under the tube. This is mainly due to the weakening of support stiffness caused by the vertical pile group effect. The pile group effect is weaker due to the fewer number of piles under the peripheral frame columns and angle piles.