The invention relates to the technical field of fabricated structures, in particular to a prefabricated vertical component bottom connecting device and a construction method. A hollow box-shaped structure is arranged at the middle upper part of the connecting device, and one side of the connecting device is exposed to form a groove; a threaded connection end is arranged at the upper part of the box-shaped structure and is in threaded connection with a vertical reinforcing
steel bar in the prefabricated vertical component; a
barrel is arranged at the lower part of the box-shaped structure, and a spiral rib surrounds the periphery of the
barrel; the top of the lower component is vertically provided with a vertical connecting rib, penetrates through the cylinder and is inserted into the inner cavity of the box-shaped structure for a certain length during installation, the vertical connecting rib is fixed in the groove through
bolt connection, grouting materials are injected into gaps of the inner cavity of the cylinder in the later period, and the grouting materials are hardened to form a whole. According to the invention, the structure is reasonable, the connection is reliable, the on-site installation speed of vertical members such as prefabricated walls and columns can be greatly improved, an inclined support is omitted, the construction cost is greatly reduced, the vertical tension and compression force transmission and
horizontal shear resistance of the vertical steel bars can be realized, and the anti-seismic property and the
structural safety of a fabricated building can be ensured.