The invention relates to a vertical pile underpinning and pile hole sealing method of a thick plate basic structure of a building, comprising the following steps of: (1) drilling a vertical pile hole on the thick plate base by using a machine tool and installing a pile below the vertical pile hole; (2) respectively clearing gaps under the thick plate base and on both sides of the pile top; (3) downwards placing a pile top transverse anti-punching steel bar net in the vertical pile hole, respectively placing both ends of the pile top transverse anti-punching steel bar net in the gaps cleared on both sides of the pile top in advance; and (4) sealing pile heads. The steps (3) further comprises the steps of: firstly, holding the knob of a steel bar to place the pile top transverse anti-punching steel bar net into the vertical pile hole, wherein one end of the net droops, and the other end tilts; then, placing the drooped end of the net into the gap of one side; dragging the knob of the steel bar, placing the other end of the net in the gap of the other gas, and horizontally arranging the net on a steel base plate prefabricated on the pile top. By adopting the invention, the hard work of manual inclined cone hole drilling can be relieved.