Abstract: Aiming at the existing methods of long inspection cycles, failure to identify subtle fault symptoms, delay in processing time, and causing vicious accidents such as equipment injection, explosion, fire, etc, this paper introduces a design of an intelligent detection device for narrowband IoT（NB-IoT） data transmission solution, and the detection system is divided into perception layer, network layer and application layer, which minimizes the risk of sensor installation while maintaining the original structure of the device, and adopts a portable design, plug and play. NB-IoT has advantage that the coverage is wide, the transmission is stable, the abnormal working conditions of the equipment can be quickly identified and diagnosed, and early detection and early treatment of equipment failures are realized. It is proposed to formulate double criterion standards for oil level and oil temperature, further optimize the online monitoring method based on the oil and gas pressure monitoring device, and the equipment intelligent pre-diagnosis technology is used to facilitate personnel to perform horizontal and vertical comparison of current transformer.