A compensation method for a display panel, a compensation device for a display panel, and a display apparatus are provided. The display panel includes a plurality of pixel units, and each pixel unit includes a pixel circuit and a light-emitting element. The compensation method includes: detecting a threshold voltage of a drive transistor in the pixel circuit; detecting a maximum data voltage corresponding to a maximum brightness of the light-emitting element; and based on the threshold voltage, the maximum data voltage and an expected display brightness, calculating a compensation display data voltage in a normal display state after the display panel is compensated.