An outdoor lighting system comprises an outdoor light source, a luminance control device, a detection apparatus, a communication network and a main controlling system. The detection apparatus is configured for detecting a luminance of the light source and generating a corresponding detecting signal associated with the luminance of the light source. The main controlling system receives the detecting signal from the detection apparatus via the communication network, and generates a luminance control signal in responsive to the detecting signal; the luminance control device is configured for receiving the luminance control signal via the communication network and regulating the luminance of the light source according to the luminance control signal.