For improving safety degree of wind tunnel flexible nozzle profile monitoring system operation, design flexible nozzle profile monitoring system. Combine with the flexible nozzle characters, use rotating encoder and travel switch to realize position monitoring of flexible nozzle profile, use oil pressure and straight line position sensor to realize hydraulic operation monitoring, establish ring net based on EtherCAT technology, realize distributed collection and centralized data processing by bus technology, and put forward man-machine monitoring scene and practical failure diagnosis method. The operation results show that the system can efficiently realize flexible nozzle profile monitoring in real time, and improve operation safety degree of flexible nozzle.