Knowing the distribution of sky luminance at any time is the foundation to make full use of natural light and realize intelligent lighting. Based on the CIE 15 sky types and the sky luminance formula, calculation methods of the parameters in the sky luminance formula are studied. Using this method, we only need to know the local latitude, date and sky type that the sky belongs to, and the distribution of sky luminance at any time can be calculated. Based on the existing reliable measured data of sky luminance distribution, the calculated values of the sky luminance distribution and the measured values are compared, and the differences between the calculated and measured values are analyzed. The results show that, the calculated data of the sky luminance distribution are in good agreement with the measured data, so the measured data can be replaced by the calculated data as important data for the energy-saving light regulating.