The invention discloses a communication line fault detecting device and method. The communication line fault detecting device comprises a sending module, a receiving module, a computing module and a judging module, wherein the sending module is used for transmitting a prestored test code through a communication line required to be detected; the receiving module is used for receiving the test code transmitted by the communication line, and the test code is taken as a receiving code; the sending module is connected with the receiving module through the communication line required to be detected; the computing module is used for comparing the test code with the receiving code and determining an error rate; and the judging module is used for determining whether the communication line breaks down according to the error rate. Therefore, when the communication line breaks down, all that is required is that a worker takes the device provided by the invention to a scene where the fault happens to detect the communication line instead of taking multiple fault detectors or selecting different fault detectors according to different detected communication cables, so that the labor intensity of the worker is reduced.