The development of Internet of Things (IoT) has broken through the limits of old technologies on the networking and communication of automation system for dam safety monitoring. A super-large automation system for the safety monitoring of Xiluodu Hydropower Project is constructed with distributed and multi-level communication network using large amounts of intelligent acquisition devices based on M2M IoT technology. Tests during the construction of the system evinces that the system improves the speed of data acquisition remarkably on the premise of ensuring accuracy and reliability.The safety monitoring automation system of Xiluodu Hydropower Station is advanced, stable, compatible and expansible with strong secondary development ability convenient for expansion in later stage to meet demands of all construction parties.