Wood-plastic tray bottom beam and extrusion die thereof

The utility model discloses a wood-plastic tray bottom beam and an extrusion die thereof. The wood-plastic tray bottom beam comprises a top surface and a bottom surface which are parallel to each other, and two arc-shaped side surfaces which shrink inwards, the wood-plastic tray bottom beam is provided with an upper pair of weight-reducing cavities and a lower pair of weight-reducing cavities which are symmetrical about an axial plane; a top plate and a bottom plate with uniform thickness are formed among the top surface, the bottom surface and the weight reduction cavity, and a longitudinal supporting wall is arranged between the top plate and the bottom plate along an axial plane and is vertically connected with the top plate and the bottom plate; arc-shaped side walls with the uniform thickness are formed between the side faces and the weight reduction cavity, and a transverse supporting wall is arranged between the arc tops of the two arc-shaped side walls. And the transverse supporting wall and the longi