Using UDEC discrete element method (DEM) and field monitoring method, the influence rules of slope height, slope angle and excavation stage on the stress field, displacement field and stability safety factor of high steep slope during excavation process were investigated. Research shows that: (1) The slope displacement and maximum principal stress gradually decrease and increase from the face (top) to the bottom of slope and from the middle (lower) part of the final excavation face to both sides of slope respectively, and the maximum displacement and stress increase and decrease with the increase of slope height (angle) respectively (decrease and basically remain unchanged with the increase of excavation stages respectively). (2) The curve of slope shoulder (top) displacement versus excavation times can be roughly divided into three development stages, i.e., the early stage of steep increase, the middle stage of gradual increase and the later stage of gentle decline (slope shoulder), gentle decline-steep increase or steep drop-slow increase (slope top). (3) Under the same slope height (angle) or excavation stages, the safety factor of slope stability first increases and then decreases with the increase of excavation times, and it decreases with the increase of slope height (angle) under the same excavation times (increases with the increase of excavation stages). (4) The results of numerical simulation reveal the real-time stress and deformation state of high steep slope in the process of multi-stage excavation, which is in good agreement with the field monitoring results. It is suggested that dynamic information design, construction and monitoring should be adopted for multi-stage high steep slope excavation engineering.