Bending tests of six large-diameter post-tensioned prestressed concrete piles are carried out by the four-point bending method, and the cracking capacity and ultimate bearing capacity are obtained. The results of bending tests are compared with those for other piles widely used in China. The results show that the flexural performance of large-diameter post-tensioned prestressed concrete pile is better than that of other piles, so we can conclude that the ultimate flexural capacity of concrete piles can be improved by increasing the effective prestress within a small range. We also find that the length of cantilever is important in bending test, and the recommendable length of cantilever is between 0.08L and 0.1L.