A display substrate, a preparation method and a brightness compensation method therefor, and a display apparatus are provided. The display substrate includes a drive structure layer disposed on a substrate, a light-emitting element disposed on the drive structure layer, and a light detection unit which is disposed on the light-emitting element and is configured to detect the brightness of the light-emitting element, wherein the drive structure layer includes a pixel drive circuit, the light-emitting element includes a first electrode, an organic functional layer and a second electrode which are stacked on the drive structure layer, and the first electrode is connected to the pixel drive circuit; and the light detection unit includes a third electrode, a photosensitive active layer and a fourth electrode which are stacked.