Disclosed is a substrate support structure, a vacuum drying apparatus and a method for vacuum drying a substrate. The substrate support structure comprises: a support pin having a top end for supporting a substrate; and an auxiliary support assembly including: a drive device; a support rod driven by the drive device; and a support disc disposed at a top end of the support rod and made of flexible material adapted to support the substrate, wherein the drive device is configured to drive the support rod to move in a direction parallel to an axial direction of the support pin so as to make the support disc positioned below or above the top end of the support pin as the support rod moves, so that the substrate is selectively supported by the support disc or the support pin. The substrate support structure, the vacuum drying apparatus and the method for vacuum drying a substrate can prevent the substrate from being easily scratched and avoid poor quality and uneven brightness of the substrate.