The invention provides a rapid construction method for an over-wet soil roadbed. According to the natural water content, the compaction control water content, the seepage coefficient and the air inflow value of over-wet soil filling, the wind speed and the wind temperature are determined. Through rapid dehumidification equipment, the local environment of over-wet soil of a loose laid layer is effectively improved, the air temperature and the relative humidity of the local environment exceed the air inflow value of roadbed filling, meanwhile, the forward and reverse rotation stirring effect of an overturning and stirring wheel is adopted for assistance, and therefore the water content of the over-wet soil filling is rapidly reduced to the compaction control water content of over-wet soil. By the adoption of the method, the roadbed compaction quality is stable and reliable, the roadbed disease happening time is greatly delayed, and the use efficiency of a road surface is effectively improved; the technical problem that it is difficult to ted the over-wet soil within the set time to reach the compaction control water content under the rainy climate condition in South China due to the fact that the over-wet soil is high in water content is solved, the use rate of the over-wet soil is greatly increased, the construction efficiency of the over-wet soil is greatly improved, a construction period is shortened, and the manufacturing cost is saved; and the technological cost is low, the roadbed quality is good, and economic benefits are remarkable.