Combined with the pile foundation engineering of a super-large highway bridge, vertical static loading test of pile with expanded diameter was carried out. The pile’s load-settlement curves, axial forces of the different pile’s section and the pile-soil interaction friction were obtained from the test. The load transfer mechanism and bearing behavior of the pile with expanded diameter under vertical load were studied. The results show that the ultimate load of the testing pile is more than 6000kN. The pile-soil interaction of the pile with expanded diameter behaviors as friction pile, and the bearing capacity of the segment with expanded diameter accounts for 40% of the ultimate load. These studies provide important references for similar projects.