The present disclosure discloses a method and device (302) for adjusting grayscale of display panel, the method includes: performing image capture on the display panel, and obtaining a current image (S10); identifying an uneven area in the current image, and detecting original output brightness and original input grayscale of the uneven area (S20); determining a target input grayscale corresponding to a preset target brightness according to actual Gamma curve value which is obtained by testing the display panel (S30); using the difference between the original input grayscale and the target input grayscale as grayscale compensation value of the uneven area (S40).