The invention discloses a rigid-flexible drainage body and a construction method thereof. The rigid-flexible drainage body comprises a rigid drainage body, a connecting disc, a plastic drainage plateand a press-in mold. A connecting cavity is formed in the connecting disc. The connecting disc is connected with the rigid drainage body and the plastic drainage plate. A through drainage channel is formed by the plastic drainage plate and the rigid drainage body through the connecting cavity in the connecting disc. The rigid drainage body comprises a water-permeable steel pipe, a reverse filter layer, water-permeable filter cloth and a conic plate head. A floral hole is formed in the water-permeable steel pipe. The outer portion of the water-permeable steel pipe is sleeved with the reverse filter layer, and the outer portion of the reverse filter layer is wrapped by the water-permeable filter cloth. The conic plate head is welded to the lower portion of the water-permeable steel pipe. Thedrainage body can be put in to-be-treated super-soft soil through the press-in mold of the drainage body and can also be arranged in a dredger fill storage yard in advance. Recycling can be achieved,the drainage body and the soil can generate compression deformation together (the plastic drainage plate), and the situation that vacuum pressure cannot be directly applied to the surface layer of the soil due to the fact that the drainage body cannot be compressed can be avoided in the vacuum pre-pressing process.