Color temperature and correlated color temperature (CCT) are important parameters of the LED light sources. The procedure for calculating colorimetric parameters,such as color coordinates (u,v) and CCT from spectra data,is rather complicated. An advanced algorithm is necessary to simplify the computation. Based on the definition of chromaticity,the advantages and disadvantages of three classical CCT algorithms are analyzed,respectively,and a new dichotomy optimization algorithm is proposed,whose principle and procedure are illustrated in detail. By comparing the results of dichotomy with the other classical algorithms by Planck formula and actual white LEDs spectra,it is proved that the dichotomy is a CCT algorithm with higher accuracy and faster speed.