In this paper a hybrid light model is proposed based on the 1931CIE standard using cold and war m white light emitting diodes (LEDs) and two-channel pulse width modulation (PWM).From the theoretical model,the relationships betwe en chromaticity coordinate,of mixed light source,correlated colour temperature,maximal luminance,colour ren dering index and the radio of duty ratio of two-channel PWM are derived.A mixed colour experiment is conduct ed using two white LED samples with cold (3282K) and warm (12930K) color temperatures respectively.LED drive power and the proportion between cold and warm white light are controlled by a micro-controll er via the PWM output signal.The experimental results of chromaticity coordinate of mixed light source,correlate d colour temperature,maximal luminance and color rendering index agree with the theoretical values very well, suggesting the theoretical model is valid.Theoretical and experimental results also show that the mixed white light with low color temperature,high color rendering index and high luminous flux can be obtained when the ratio of duty cy cle of two-channel PWM is around 1.