Two centrifuge model tests were carried out to study the mechanism of reinforcing composite foundation with flexible non-uniform piles under embankment load. One centrifuge model is with non-uniform piles (new type embankment), and the other with piles of equal length (traditional embankment). Several miniature pore pressure transducers (PPTs) and earth pressure transducers (EPTs) were installed in different depths of earth in the tests. Displacement sensors were arranged at key points on the embankment surface. The results obtained from the two centrifuge tests showed that the pile-soil stress ratio of longer piles in the new type embankment increased remarkably. When the total length of non-uniform piles was equal to that of uniform piles, the new type embankment had a less total settlement than traditional embankment at the top of the piles. Furthermore, the lateral settlements of this new type embankment were less than those of the traditional embankment.