With the development of urban infrastructure construction, the current management of urban manhole cover is widespread, it is difficult to achieve unified management, and the problem of damage and theft of the manhole cover cannot be found in time. This paper proposes an intelligent manhole cover communication alarm system based on narrowband Internet of Things (NB-IOT). The sensor uses real-time monitoring of manhole cover information. The NB-IOT terminal module sends status information to the base station, and the base station connects with the core network of NB-IOT. The status data is sent to the cloud platform, and the background management system can obtain the fault information of the manhole cover in real time. Through a large number of experimental tests, the intelligent manhole cover communication mechanism proposed in this paper is to meet the requirements of low power consumption and can accurately detect the fault information of the manhole cover.