Making full use of the advantages of narrow band Internet of things（NB-IoT），the safety monitoring system of water conservancy project is designed and developed.A water conservancy project safety monitoring instrument based on narrow-band Internet of things（NB-IoT）transmission data is designed，which realizes the informatization of water conservancy project safety monitoring，and realizes the real-time monitoring of water conservancy project safety information based on Web page.The system can monitor the seepage of dam body and dam foundation by monitoring the change of seepage pressure and temperature value in the water conservancy project building with the osmometer，which is especially suitable for the water conservancy project building that needs regular observation，has great potential safety hazard and is difficult to deploy the wired network，so as to improve the safety information management level and management efficiency of the water conservancy project．