Research conclusions: The pile-slab structure subgrade is a new type of subgrade structure of ballastless track railway with high bearing capacity, dynamic performance and better economical efficiency. So it can be applied to the soft foundation improvement in the low embankment and cutting section where the engineering geology is complicated and in the special section where the short subgrade is between two bridges(tunnels ) and subgrade in the switch section of newly-built ballastless track railway of passenger dedicated line, simultaneously to the reinforcement and stabilization of the built embankment.