Dimming lighting sources are the basic parts of intelligent illumination. Fully utilizing the controllable performance of light emitting diode (LED), the dimming dynamic lighting LEDs are made successfully by cold/warm white LEDs and two channels′ pulse width modulation (PWM). According to photometric and colorimetric quantities of the selected cold/warm white LEDs, and the needed mixed color lighting sources, calculation model of duty cycle which controls the outputs of them are established. The constraints of duty cycle with correlated color temperature (CCT) as an objective parameter are also analyzed. Experiments show that not only the up-and-down luminous flux is less than 2.5%, and the deviation of CCT is less than 10 K when CCT of the mixed color lighting sources are changed, but also the CCT keeps unchanged when the output luminous flux is altered. Meanwhile, the analytic process of actual parameter design of mixed color lighting sources is in accordance with the selected performance parameters of lighting soures, which shows that the method is direct and has good practicality.