A device and a method for processing a waited display picture of an OLED display device are provided. The device includes a block dividing unit for dividing a waited display picture into multiple blocks; an average grayscale determining unit for determining an average grayscale value of each block; a high grayscale determining unit for determining a block having an average grayscale value greater than a preset threshold value as a high grayscale block; an adjacent grayscale determining unit for determining an adjacent grayscale value of each high grayscale block; and a regulation unit for adjusting grayscale values of pixels of each high grayscale block. The present invention adjusts grayscale values using a block as a unit. Besides, the difference of luminous efficiency or light transmittance of different color components is also considered so as to effectively improve the life of the OLED display device.