The invention relates to a color battery assembly with a downward-transfer function for a spectrum, belonging to the technical field of solar photoelectric conversion. The color battery assembly comprises a solar battery array, the front area of the lighted surface of a battery slice of the solar battery array is provided with a spectrum downward-transfer optical medium layer; the spectrum downward-transfer optical medium layer absorbs a short wave range with poor battery spectrum response and transfers the short wave range with the poor battery spectrum response to a long wave range with ideal battery spectrum response and then carries out the photoelectric conversion through the battery slice; and the spectrum downward-transfer optical medium layer comprises a medium and semiconductor quantum dots, wherein the semiconductor quantum dots are uniformly dispersed in the medium, refer to nanoparticles of II-VI group compounds and have homogeneous or heterogeneous multi-layer structures.The color battery assembly is provided with common medium layers on the lighted surface and the backlight surface of the spectrum downward-transfer optical medium layer, enhances the response of the color battery assembly on short waves of a solar spectrum and effectively reduces the battery heat effect.