A backlight setting method of an analog instrument panel is provided. Through a cooperation between a microprocessor and an electronic control circuit, the backlight of the analog instrument panel can be cyclically varied. Moreover, the present invention employs the key set mounted outside the instrument panel to be pressed by the user for choosing a favorite backlight color during the backlight of the instrument panel is mixing changed. Furthermore, because the program design in the microprocessor, the illuminating element, through an asynchronous color mixing theory, can provide various colors to be set by the user for complying the backlight of the analog instrument panel with the like and demands of the user.