Prewarning system and crane

The utility model provides a prewarning system and a crane. The prewarning system comprises an acquiring unit, a judging unit and an executing unit, wherein the acquiring unit is used for acquiring a position signal of a barrier and sending the position signal to the judging unit; the judging unit is connected to the acquiring unit and is used for judging whether the barrier is located in an operating region of the crane according to the position signal and sending a command to the executing unit when judging that the barrier is located in the operating region of the crane; and the executing unit is connected to the judging unit and is used for prewarning and/or forcefully stopping the crane from acting according to the command. According to the technical scheme provided by the utility model, since whether potential safety hazards occur in the operating region of the crane is detected in advance and prewarning protection is carried out when the detection result shows that a barrier exists in the operating reg