For the problem of the inaccurate automatic white balance of digital camera and the color reproduction is not true, an automatic white balance algorithm is proposed based on the L*a*b* color space. The algorithm according to the color space conversion, first converts sRGB picture to L*a*b* color space; then using grey world model executes color collection for color components of a* and b* in the L*a*b* color space; finally converts L*a*b* picture to sRGB color space. Experimental results show that the automatic white balance for images in the L*a*b* color space obtains good effect of color reproduction.