Ultra-thick bottom plate surveying and setting out construction method and setting out platform

The invention discloses an ultra-thick bottom plate surveying and setting out construction method and a setting out platform, and belongs to the field of construction. The ultra-thick bottom plate surveying and setting out construction method comprises the steps: repeated soil excavation and support construction are conducted in a foundation pit; the setting out platform is erected on the lower part of a last support and the upper part of the finished face of a bottom plate; a cushion layer, a waterproof layer and a waterproof protecting layer are constructed, and control points are distributed on the setting out platform; the control points serve as the datum, and an axis net is put onto the waterproof protecting layer; through the put axis net, lower skin steel bars of the bottom plate are constructed; the axis net is put onto the lower skin steel bars; a steel bar supporting frame is completed, and upper skin steel bars are bound; the axis net is put onto the upper skin steel bars;and the axis net on the u