A display driving circuit, a driving method thereof, and a display device are provided. The display driving circuit includes: a timing controller which is configured to acquire grayscale data of subpixels in a frame of display image row by row and output the grayscale data to the grayscale controller; a grayscale controller which is configured to receive grayscale data of each subpixel in each row of subpixels, and control at least a part of the plurality of reference grayscale voltage output terminals in the grayscale controller to output reference grayscale voltages according to the grayscale data of each subpixel in each row of subpixels; a source IC which is configured to generate a grayscale voltage according to the received reference grayscale voltages and input the grayscale voltage as a data voltage to a data line.