The invention provides an ecological reconstruction method for the plant diversity after returning of an abandoned farmland to a marsh wetland, and relates to a method for reconstructing the plant diversity of the marsh wetland.The method is used for solving the problem that after the process of returning the abandoned farmland to the marsh wetland, the plant diversity of the abandoned farmland marsh wetland is difficult to recover.The method comprises the steps of 1 abandoned farmland surface soil removing; 2 natural wetland soil propagule bank collecting; 3 abandoned farmland soil propagule bank introducing; 4 hydrological controlling of the abandoned recovery farmland; 5 non-target species removing in the initial stage of reconstruction.The method is simple, convenient and high in reconstruction speed, can be widely applied to ecological reconstruction of the abandoned farmland marsh wetland in the north and is suitable for reconstructing the plant diversity of the marsh wetland.