The invention embodiment discloses a network situation detection system. The network situation detection system includes a detection signal generating module, which is used for producing detection signal, and broadcasting the detection signal to the multi network units by the branching unit, receiving the reflected signal produced by the detection signal in the network line, and detecting the power value sequence of the reflected signal of the detection signal, wherein the detection signal includes a reference test signal and a first test signal; a waveform analysis module which is used for obtaining the power value sequence of the reflected signal of the first branch circuit link, according to reference power value sequence of the reflected signal of the reference test signal as well as the first power value sequence of the reflected signal of the first test signal; as well as a filter, which is used for filtering signal through the first branch circuit link. The network situation detection system disclosed by the invention embodiment can obtain the power value sequence of the reflected signal of the branch circuit link, and detect the situation of the network circuit.