The invention discloses a wet and soft soil foundation treatment method which comprises the steps of 1, backfilling completely within the roadbed width range; 2, before roadbed construction, firstly, removing surface water, and then removing the surface layer salinized soil and surface organic matter of a construction region; 3, backfilling gravel soil within the treatment range, and carrying out primary rolling; after rolling is finished, leveling to form a cross slope; 4, excavating two trapezoid drainage ditches respectively at the two sides of a roadbed; 5, laying a plastic drainage plate; 6, dynamic compaction, compacting by points for twice and fully compacting for once; 7, after dynamic compaction treatment, rearranging the roadbed, and cleaning the overground part of the top of the drainage plate; laying a middle coarse sand cushion layer as a drainage channel, wherein the gradient of the middle coarse sand cushion layer is equal to that of the roadbed; placing a bending part of the plastic drainage plate in the center of the sand cushion layer to enable the bending part to be communicated with the sand cushion layer; 8, backfilling gravel soil onto the middle coarse sand cushion layer; 9, after the roadbed is finished, laying gravel on the surface layer, rolling and compacting.