The utility model discloses a top-layer support of a driving device of a full-rotation casing pipe drilling machine. a box-type symmetrical structure with an optimized structure size is adopted; the device is mainly composed of a guide supporting device, an upper platform fixed to the upper end of the guide supporting device, a bottom cover plate fixed to the guide supporting device and located below the upper platform, a side sealing plate assembly fixedly arranged between the upper platform and the bottom cover plate, a plurality of locking oil cylinder bottom mounting bases and a pluralityof stand column positioning devices. Through various strengthening modes, the overall structural strength and rigidity are effectively improved, and the distribution balance of various loading forceson the top-layer bracket is improved; the drilling device is compact in structure, good in structural rigidity, reasonable in stress distribution, high in drilling vertical precision, stable and reliable.