In an intelligent monitoring system, a wireless signal processing device transmits a wireless signal toward a first target object in a monitored area, receives a wireless status signal, and generates a monitoring signal corresponding to the first target object according to the wireless status signal. In addition, at least one signal-relaying device receives a back scattering signal, which is reflected from the first target object in response to the wireless signal, transfers the back scattering signal into the wireless status signal, and transmits the wireless status signal to the wireless signal processing device. The signal-relaying device includes a power supply device for supplying power for operations of the signal-relaying device, and the signal-relaying device is disposed in the monitored area between the first target object and the wireless signal processing device.