The article presents solutions for designing, building and evaluating the accuracy of automatic monitoring system by robotic total station when continuously monitoring horizontal displacement of Hoa Binh Hydropower Plant . The system is designed and built put into operation and used for horizontal displacement monitoring results with high reliability and stability with accuracy of horizontal displacement less than 2.5 mm, for continuous and instantaneous data collection frequency, data can be extracted at any time according the erratic changes of weather, natural disasters or the change of reservoir water level and automatically send an alarm when the horizontal displacement value at the monitoring points reaches the alarm threshold. Continuous horizontal displacement monitoring is the basis to add settlement measurement cycle to check the settlement of the dam when there are abnormal signs of horizontal displacement.