Abstract: This paper introduces the slope monitoring technology and method, and takes the Dagushan iron ore abandoned dump slope monitoring project as an example, using GNSS online monitoring technology to comprehensively analyze the slope deformation monitoring data, and the safety status and stability of the slope are evaluated.The research shows that the settlement displacement in the monitoring area of the abandoned dump slope of Dagushan iron mine is generally greater than the horizontal displacement, and the fluctuation trend of settlement displacement is significantly higher than the horizontal displacement.It can be seen that the slope deformation of Dagushan dump is mainly caused by sedimentation.The settlement curve of each monitoring area fluctuated significantly from July to September of 2017 and from December of 2017 to February of 2018, showing a trend of decreasing first and then increasing, and it is consistent with the situation that the monitoring area is affected by the summer rainfall and the snow and ice frost heave in winter.And the impact of rainfall on the deformation of the monitoring area is greater than the impact of ice and snow frost heave.The lower part of the monitoring area of the pellet factory, Huanglingzi village and landslide area is generally larger than the upper part deformation and the horizontal displacement and settlement displacement of the tailings monitoring point adjacent to the landslide area are slightly higher than other monitoring points in the tailings pond.Since the bottom of the slope is close to the factory area or residential area, it is necessary to pay attention to the deformation of the bottom of the slope and strengthen the monitoring to ensure the stability and safety of the slope in the area.According to the comprehensive analysis, the monitoring area of the pellet factory is the most deformed in the four monitoring areas of the abandoned dump slope of Dagushan iron mine.The Huanglingzi village and the landslide area are the second, and the tailings pond monitoring area has good stability.The research results have reference significance for the monitoring and early-warning of similar mine slope engineering.