A method of color images separation and printing for spot printing technology is presented. A combination of inks for printing images is selected by genetic algorithm according to the information of both original color images and given inks. Then a numerical optimization algorithm is used to compute the separations of color images with customization inks. With the ability of producing the same or more vivid reproduction than tradition four-process color printing with just a small number of inks, this method can be widely applied in many industries such as printing, dying and ceramics trades, etc.