A LED illumination system includes a signal inputting module, a driving module, a switch module, an illumination module, a sampling module, and a control module. The signal inputting module receives a selection signal that corresponds to one specific color temperature and generates a first voltage signal based on the selection signal. The driving module generates a driving signal based on a color temperature adjusting signal. The switch module includes a plurality of LED control units whose activation status that the illumination module responds to illuminate. The sampling module samples the output current of the switch module and generates a second voltage signal correspondingly. The control module receives the first voltage signal and the second voltage signal and generates a control signal correspondingly. And the control module relays the control signal. The switch module additionally controls its illumination status based on the driving signal and the control signal.