The utility model provides a rope-loosening protective circuit and a system circuit, and belongs to the industrial safety field. The rope-loosening protective circuit comprises a rope channel micromotion switch in series connection with a coil loop of a first relay, a first normally-open contact and a first dynamic contact connected with a system safety return circuit in series, also a first normally-closed contact of the first relay and a rope-loosening indicator in series connection with the first normally-closed contact; the first normally-closed contact and the rope-loosening indicator are connected with the rope channel micromotion switch in parallel, when the rope channel micromotion switch is disconnected, the first normally-closed contact is triggered to be closed and connect with the first dynamic contact so as to trigger the rope loosening indictor to alarm. In the utility model, the rope channel micromotion switch is connected with the first relay in series, when the steel rope has loosening fault, the system safety loop is triggered to be disconnected and the rope loosening indicator is triggered to alarm at the same time, meanwhile the rope loosening indicator alarms to accurately locate the fault of the disconnected system safety loop, thereby reducing the fault location time.