Light mixing method, system and device of RGB-LED light source

The invention discloses a light mixing method, system and device for an RGB-LED light source, and the method comprises the steps: obtaining the junction voltage of three primary colors of red, green and blue in real time during working, and obtaining the junction temperature at the current moment through a voltage difference determined by the junction voltage and a reference junction voltage, and a change trend model of the junction temperature; on the basis of the junction temperature at the current moment, color coordinates and brightness of respective LEDs of corresponding three primary colors at the current temperature are obtained by combining the color coordinates of the red, green and blue primary colors and a change trend model of the brightness along with the junction temperature; and based on the color coordinates and brightness of the target color and the color coordinates and brightness of the LEDs corresponding to the three primary colors at the current temperature, the duty ratio of the three pr