A rapid white balance method for color digital image is disclosed. This method is applied to RGB color regions in an image. First, the image is divided into several blocks to obtain the G parameter, then the averaged R and B parameters of each block, thereby obtaining the R and B parameters of the whole image. Using the R and B parameters, the method obtains an R gain and a B gain. Finally, the image is adjusted. The method only uses one RGB value for each pixel. The processing time is reduced, while the quality of the image is increased.