| Rockfall, landslide and mudflow caused by slope stability failure which is a common problem in the range of engineering field such as mining engineering, civil engineering, railway and highway engineering, hydrological and hydroelectric engineering, waste residue and garbage management engineering, together with earthquake and volcano eruption are considered to be the most disastrous geological hazard all around the world. In recent years, as the swift development of infrastructure facilities in the field of mining industry, hydroelectric industry, transportation and construction industry, the scale of construction increases and also the investment strength, the problem we need to deal with extend gradually from simple soil slope to complicated high rock slope, the potential of slope stability failure and also the disastrous effect becomes ever more prominent, it is in these condition that the research of high rock slope stability has become a researching hot spot.The engineering geological condition and regional geological condition of some southwestern China high rock slope was introduced and analysed, several limit equilibrium methods such as simplified Bishop method, Sarma method were employed, several different excavating and supporting methods and also different working conditions were involved to evaluate the stability of the slope . Especially important is the employment of the FLAC3D method to numerically simulate and analyse the internal stress and movement of the slope, the results were studied and compared with data collected from in-situ monitoring. A series of useful tips which were helpful for the designers were derived from using the back analysing method to obtain rock parameters. The problems that were discussed in this paper are as follows:It is first introduced in this article several methods to analyse the stability of slopes, such as the limit equilibrium methods, numerical methods and back analysis method. The engineering geological condition and regional geological condition of some southwestern China was studied, the rock mass parameter assignments were evaluated and restricted in a small region. Several representative cross-sections with different soil layers and different combination of faults and joints, under conditions like normal excavation sequence, instant downpour, and 8 degree of Richter scale earthquake, supported by various cables installing sequence were analysed to compute the safety coefficiency before and after cable installation. The results could be used to assess the stability of the rock slope and the efficiency of cable installation.FLAC3D (Fast Lagrangian Algorithm for Continua) is then introduced as a selective numerical method to be used in geotechnical engineering, its principal, its feature and its usefulness in geotechnical field is highlighted and elaborated. To show to readers how this kind of method could be employed to solve real problems, a representative section of a high rock slope is then employed to be analysed. A model is then constructed by means of imputing ANSYS grid into FLAC3D, then several control points are distributed to the edge of every cat walks to monitor the both horizontal and vertical displacement, inner stress, strain and plasticity region are also monitored during the excavating and cable installing procedure. The results are then analysed to be compared with results collected before excavation or with results after cable installation to see the stability of slope and the effect of cable installation.Last but not least, real-time monitoring results were collected and sorted, representative data could be chosen to be compared with computed ones, thus could be used as inputs in back analysis to sort out real parameters in the wild. This example confirms FLAC3D's usage in the geotechnial field to be an effective way of analysing the stability of high rock slope, it can also be instructional to decide at which time to do the excavating work or cable installation work, serve the construction work well indeed.
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