The invention relates to a gamma curve correction method. The method comprises the following steps that: (A) an arithmetical device sequentially transmits different color scale data to the driving unit of a device to be tested, wherein the color scale data are corresponding to a plurality of brightness setting values respectively; (B) whenever receiving a batch of color scale data, the driving unit generates an image corresponding to the color scale data so as to drive the display unit of the device to be tested to display the image with one brightness setting value corresponding to the color scale data; (C) a measuring device measures the optical characteristics of the display unit, generates a corresponding measurement result and transmits the measurement result to the arithmetical device; (D) the arithmetical device generates a corresponding correction coefficient according to the measurement result and transmits the correction coefficient to the driving unit of the device to be tested; and (E) the driving unit updates the corresponding brightness setting values according to each correction coefficient.