Abstract: The earthquake-induced soil liquefaction can result in serious damages to pile foundations. Therefore, it is an important task to study the failure mechanisms of pile foundations in liquefaction soils in earthquake geotechnical engineering. Until now, the seismic behaviors of pile-soil-structure systems have not been fully understood yet. Most of current researchers are focused on strength failure of pile material, in which it is difficult to consider complex influencing factors such as lateral spreading of liquefying soils, pile buckling, and dynamic interaction between soil and structures. In this paper, firstly, a series of damage cases of pile foundations in liquefied soils are summarized from historical reports in Chian and abroad. Then, the failure mechanisms of pile foundations as well as research advances are introduced and analyzed in detail. Finally, aimed at liquefaction soils, it is pointed out that further investigations on the failure mechanisms of pile foundations should be strengthened on the following issues (1) pile buckling instability in liquefying soils; (2) novel numerical simulation methods for pile failures in liquefaction soils, e.g. continuum elasoplasticity-fluid dynamics coupled method; and (3) dynamic interaction analyses of pile-soil-structure systems in liquefaction soils.