Embodiments of the present disclosure provide gamma correction method and device for a display module. The gamma correction method includes: determining, for each sub-pixel of a display module to be corrected, the highest data voltage and the lowest data voltage after gamma correction of the highest gray scale and the lowest gray scale of the display module; determining at least one set of alternative gamma register values that are capable of performing gamma correction of the display module; determining at least one set of gamma register values to be corrected for respective gray scales before the gamma correction of the display module; and performing gamma correction of the display module by adjusting the gamma register value corresponding to the gray scale to be corrected which needs to perform gamma correction.