The invention relates to the technical field of building decoration, and particularly discloses a wall body decoration structure and a construction method thereof. The wall body decoration structure comprises a suspended ceiling which is used for decorating a roof and a wall plate which is used for decorating a wall; the suspended ceiling comprises a flat ceiling and a secondary suspended ceilingwhich is arranged below the flat ceiling; the wall body decoration structure is characterized in that the secondary suspended ceiling comprises a suspended ceiling frame body; the suspended ceiling frame body comprises outside plate, a bottom plate and an inside plate which is connected with the wall; the upper end and the lower end of the outside plate are respectively bent outwards to form firstprotective edges; a first accommodating groove is formed among the first protective edges and the outer wall of the outside plate; the left end and the right end of the bottom plate are respectivelybent outwards to form second protective edges; a second accommodating groove is formed among the second protective edges and the outer wall of the bottom plate; a coating layer is paved in each of thefirst accommodating groove and the second accommodating groove, and a putty layer is arranged below the coating layer. The surface of the wall body decoration structure is pre-coated with the coatinglayer, so that the wall body decoration structure has air permeability and water absorption property; the dryness and humidity of air can be adjusted; the putty layer and the coating layer can be coated and filled uniformly in a factory without field construction, so that the wall body decoration structure is convenient and quick to install.