The relationship between color quantity in color computer-generated holography (CCGH) and computer display colorimetric system is discussed based on color transmission and matching theory. In addition, the relationship between color quantity in computer display colorimetric system and amplitude of object light field in (CCGH) is estabilished. Based on this research, the color reproduction mechanism of computer-generated color rainbow holography (CGCRH) is discussed. Then the calculation method of three primary colors and color quantity of holographic image is given.