The present invention discloses an automatic exposure method of a color camera. The method comprises a first step of reading a color image of an initial frame; a second step of comparing gray scale mean values of three components of the initial frame, and taking the component V of the largest gray scale mean value; a third step of collecting statistics about a histogram of the component V in the color image of a current frame, so as to obtain a histogram skewness of a relative middle gray scale of the histogram; and a fourth step of determining whether the histogram skewness of the current frame is the smallest histogram skewness according to a set histogram skewness minimum value and the histogram skewness of the current frame obtained in the third step, if yes, using exposure time corresponding to the color image of the smallest histogram skewness as optimal exposure time, ending, or if not, resetting exposure time, collecting a next frame of color image according to new exposure time, then returning and executing the third step to continue to search a minimum histogram skewness. The automatic exposure method of the color camera has the advantages that histogram calculation is performed by using the component of the largest gray scale value, so that the risk of over exposure of other color components is lowered.