Abstract: With the continuous development and utilization of coal resources，the slope stability of deep open-pit mine has become a major problem in slope engineering. Aiming at the low and gentle slope with small radian，GNSS on-line monitoring technology is used to establish the slope monitoring system of Hequ Open-pit Mine. By analyzing the monitoring data of each monitoring line of the slope，the slope stabili⁃ ty is evaluated and analyzed. The results show that the current slope in the mining area is basically in a sta⁃ ble state，but the displacement change value of some monitoring points fluctuates greatly. Under the influ⁃ ence of external factors，such as rainwater，freezing and thawing，spontaneous combustion of coal seam， normal operation interference and other factors，there is a possibility of landslide. According to the research results，corresponding treatment suggestions are put forward for different regions，which provides a basis for the prevention and control of slope stability in the future.

Key words: open-pit mine, GNSS monitoring technology, slope stability