The present disclosure discloses a method and a device for adjusting gray scale of a display panel, the method comprises: performing image acquisition on a display panel, and obtaining a current image; identifying an nonuniform block in the current image, and detecting an original output brightness and an original input gray scale of the nonuniform block; determining a target input gray scale corresponding to a preset target brightness according to an actual Gamma curve value, the actual Gamma curve value is obtained through testing the display panel; using a difference value between the original input gray scale and the target input gray scale as a gray scale compensation value of the nonuniform block.