The invention belongs to a sensor technology and aims at detecting whether a functional coating is invalid or not in real time. According to the technical scheme, stress between the functional coating and a base body is detected through a stress sensor, so that whether the functional coating falls off or not is judged. An insulating layer, a conductive layer and a sensor layer are prepared on the surface of the base body; the sensor layer is used for detecting the stress, the conductive layer is used for conducting a sensor signal. By adopting the sensor, the service problem of the functional coating is solved and real-time detection of the functional coating is realized. The service cycle of a base body structure can be prolonged and the overhauling time of the base body structure is shortened. When the functional coating has a peeling tendency under the action of an external force, the sensor can generate the signal and the signal is collected, positioned and amplified through a system and is stored in a specific memorizer; when retrospective detection is carried out, defects of the functional coating can be found in early time and measures can be adopted.