The invention relates to a civil engineering foundation reinforcing method, in particular to a dealing method for thick cushion layer adjusting three foundations in a main power house of a thermal power plant. The thickness of a thick cushion layer is 0.8 to 1.2 m; a dynamic compaction composite foundation and a plain concrete pile semi-rigid composite foundation are arranged below the thick cushion layer; and a cement soil pile semi-rigid composite foundation is arranged on one side of the dynamic compaction composite foundation below the thick cushion layer. Due to the fact that the 28 lime soil thick cushion layer of 1Mu in thickness is used, coordination of a dynamic compaction processed foundation and a cement soil pile processed foundation is effectively adjusted, coordination of the dynamic compaction processed foundation and a plain concrete pile processed foundation is effectively adjusted, coordination of the plain concrete pile processed foundation and the cement soil pile processed foundation is effectively adjusted, and manufacture cost is low.