To create a white LED luminaire in lower MacAdam ellipses step, the studies on prediction of change in color temperature(chromaticity coordinate) according to combination of two different CCT LEDs is needed. Therefore, this study suggested a color temperature mixing calculation based on the CIE 1931 chromaticity coordinate. Color temperature and the CIE 1931 chromaticity coordinate of mixed light could be simply calculated by using the suggested calculation without spectral power distribution measurements.